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OUTLINES  OF 

GENERAL  BIOLOGY 

AN  INTRODUCTORY  LABORATORY  MANUAL 


BY 

CHARLES  W.  HARGITT 

RESEARCH    PROFESSOR    OF  ZOOLOGY    IN    SYRACUSE    UNIVERSITY 

AND 

GEORGE  T.  HARGITT 

PROFESSOR  OF  ZOOLOGY  IN  SYRACUSE  UNIVERSITY 


FOURTH  EDITION 


LEA  &  FEBIGER 

PHILADELPHIA    AND    NEW    YORK 


641S6 


COPYRIGHT 

LEA  &  FEBIGER 

1922 


PRINTED  IN  U.  S.  A. 


QM 

3  1-7 

USLO. 


PEEP  ACE  TO  THE  FOURTH  EDITION. 


IN  preparing  the  present  edition  little  change  has  been 
made;  such  errors  as  have  been  brought  to  notice  have 
been  corrected,  and  some  changes  have  been  made  in  the 
interest  of  greater  clearness  or  more  precise  directions. 

The  ideal  underlying  the  manual  is,  as  it  always  has  been, 
to  stimulate  inquiry  and  develop  the  scientific  habit  of 
work  and  thought.  The  order  of  presentation  remains 
unchanged,  for  both  from  practical  and  pedagogical  reasons 
such  an  arrangement  has  justified  itself  through  years  of 
experience.  The  order  of  presentation  of  topics  is,  however, 
of  secondary  importance,  and  the  individual  teacher  will 
make  such  choice  of  topics  and  order  of  study  as  best 
meets  his  needs. 

An  elementary  course  in  biology  must  of  necessity  be 
limited  to  relatively  few  typical  organisms,  but  the  aim  of 
the  manual  is  distinctly  not  the  study  of  types  as  such. 
In  our  own  course  the  laboratory  study  is  planned  to  illus- 
trate general  biological  principles  such  as  the  following: 
fundamental  plans  of  animal  structure;  homology;  adap- 
tation; protoplasmic  structure  and  behavior;  development 
of  organisms;  and  other  similar  principles.  In  conducting 
such  a  course  it  is  necessary  to  make  definite  plans  ahead 
of  time,  and  select  from  the  manual  those  topics  which  cover 
the  desired  ground.  It  is  believed  that  there  is  sufficient 
material  included  to  make  possible  a  considerable  choice  to 
meet  varied  needs  and  desires. 


vi  PREFACE  TO  THE  FOURTH  EDITION 

It  is  still  a  pleasure  to  acknowledge  the  cordial  cooperation 
among  other  members  of  the  zoological  staff  in  such  sug- 
gestions as  their  several  experiences  and  observations  have 
prompted.  Should  others  who  use  the  book  feel  disposed  to 
offer  suggestions  touching  either  the  matter  or  the  method 
of  the  manual  they  may  be  assured  of  the  cordial  thanks  of 
the  authors. 

C.  W.  H. 

G.  T.  H. 

SYBACUSE,  1922 


CONTENTS. 


INTRODUCTION: 

LABORATORY  AND  APPARATUS 17 

NOTES  AND  DRAWINGS 18 

DISSECTION 21 

THE  MICROSCOPE 22 

FROG 26 

ORGANS,  TISSUES  AND  CELLS 45 

PROTOPLASM 47 

CELL  (CYTOLOGY) 50 

AMCEBA 54 

PARAMECIUM 57 

VORTICELLA 62 

QUESTIONS  ON  THE  PROTOZOA  IN  GENERAL 64 

PLEUROCOCCUS 66 

COLONIAL  PROTOZOA 68 

SPIROGYRA 70 

SPONGE 73 

HYDRA 75 

HYDROID: 

PENNARIA 80 

OBELLA 83 

MEDUSA 85 

EARTHWORM 87 

SAND  WORM 95 

FERN    . 98 

YEAST 104 

BACTERIA 107 

CRAYFISH 110 

GRASSHOPPER 116 

HONEYBEE 121 

CLAM 125 

SNAIL 133 

FISH 135 

CLASSIFICATION    .  140 


ar 

viii  CONTENTS 

.  APPE-  DIX: 

OLLECTION  AND  PREPARATION  OF  MATERIAL 147 

PREPARATION  AND  MOUNTING  OF  SLIDES 153 

REAGENTS 155 

TESTS  FOR  ORGANIC  SUBSTANCES 161 

GLOSSARY 163 

INDEX .  179 


GENERAL  BIOLOGY. 


INTRODUCTION 

Laboratory  and  Apparatus 

IN  order  to  get  the  best  results  in  a  laboratory  course 
there  should  be  cordial  cooperation  between  students  and 
instructors.  The  laboratory  should  be  orderly  and  attractive, 
and  its  schedule  regarded  with  the  same  promptness  and 
fidelity  as  that  of  the  classroom.  Certain  apparatus  is 
assigned  to  each  student  who  must  be  responsible  for  it 
during  use.  Notebooks,  dissecting  instruments,  pencils, 
and  the  laboratory  manual,  are  to  be  furnished  by  each 
student.  Each  is  expected  to  do  his  work  independently, 
faithfully,  and  to  have  his  own  outfit  which  should  be  kept 
in  the  best  possible  condition  for  effective  use. 

Ample  laboratory  material  is  furnished  for  the  work 
required,  but  it  should  be  used  with  reasonable  economy. 
This  relates  to  reagents  as  well  as  specimens.  Let  there  be 
particular  care  in  the  handling  of  models  or  museum  speci- 
mens placed  upon  the  demonstration  table.  These  are  not 
to  be  removed  from  this  table  without  express  permission. 
The  same  applies  to  demonstration  materials  and  dissections. 

At  the  close  of  the  laboratory  period,  which  may  be  ex- 
tended to  students  desirous  of  doing  extra  work,  let  the 
tables  be  cleared  up,  the  instruments,  dissecting  pans  and 
2 


18  GENERAL  BIOLOGY 

the  like  put  in  the  proper  places,  all  solid  waste  deposited 
in  receptacles  for  that  purpose,  and  only  water  or  liquid 
waste  thrown  into  the  sinks. 

Notes  and  Drawings 

Experience  has  shown  that  it  is  necessary  to  make  accurate 
drawings  and  to  write  a  definite  and  careful  description  of 
an  animal  if  one  is  to  secure  a  satisfactory  knowledge  of  it. 
The  drawings  should  be  made  (on  one  side  only)  on  un- 
ruled heavy  paper,  or  cardboard,  with  a  drawing  pencil 
(about  3H);  the  notes,  written  on  separate  sheets,  should 
accompany  the  drawings. 


FIG.  1. 

Figs.  1  to  3  are  from  drawings  which  are  correct  in  form, 
accurate  in  structure,  and  satisfactory  from  a  scientific 
point  of  view.  The  drawings  made  to  accompany  the  work 
of  this  course  should  be  in  outline  like  the  figures,  since 
shading  tends  to  obscure  rather  than  clarify  the  details  of 
structure.  The  drawings  shown  in  the  figures  demonstrate 
the  clearness  with  which  details  are  shown,  even  when  the 
structure  is  rather  complex.  However,  it  is  sometimes 
desirable  to  represent  the  texture  of  a  part  and  a  shaded 
drawing  will  occasionally  be  necessary.  Fig.  4  is  a  drawing 
of  a  group  of  cells  characterized  by  thick  walls  of  rather 
definite  appearance  and  structure.  One  side  of  the  draw- 


INTRODUCTION 


10 


ing  is  in  outline  and  shows  clearly  the  shape  and  arrange- 
ment of  the  cells  and  the  thickness  of  their  walls.    The 


Fig.  2. 


FIQ.  3. 


20 


GENERAL  BIOLOGY 


shaded  portion  illustrates  the  further  detail  of  a  certain 
structure  in  the  walls.  Fig.  5,  a  cell  in  the  process  of  divi- 
sion, is  shaded  in  a  manner  which  will  bring  out  the  details 
of  cellular  structure. 

The  following  suggestion  may  be  helpful:  Make  the 
drawings  large,  leave  considerable  space  between  them  and 
have  them  symmetrically  arranged  on  the  page.  In  start- 


FIG.  4. 


FIG.  5. 


ing  a  drawing  make  all  lines  very  faint,  and  when  the  form, 
proportions  and  arrangement  of  parts  is  satisfactory  go  over 
the  lines  with  a  smooth  continuous  stroke,  producing  a  line 
of  the  desired  strength.  The  drawing  must  represent  the 
actual  specimen  studied,  should  show  the  real  structure 
rather  than  the  mere  appearance,  and  should  be  finished 
in  the  laboratory  while  the  specimen  is  under  observation. 


INTRODUCTION  21 

Give  each  preparation  careful  study  before  starting  a  draw- 
ing. 

The  directions  for  laboratory  study  are  merely  suggestions 
with  regard  to  methods  and  order  of  work;  the  specimen  is 
the  thing  being  studied.  Do  not  be  afraid  to  do  some  things, 
or  to  make  some  drawings  not  asked  for  in  the  outlines,  if 
you  can  thereby  get  a  clearer  idea  of  the  structure  or  add 
further  to  your  knowledge  of  the  animal.  Most  of  the 
questions  asked  in  the  outlines  can  be  answered  from  the 
specimen  if  the  search  is  made,  but  if  help  is  necessary  call 
upon  the  instructor  for  aid. 

Always  give  a  clear  and  definite  title  to  each  drawing, 
indicating  what  aspect  of  the  specimen  is  shown;  also  clearly 
name  the  parts  shown  in  the  drawing.  Write  labels  parallel 
to  the  bottom  of  the  page  and  connect  to  the  part  desired  by 
faint  continuous  lines  (these  are  better  than  dotted  lines). 
The  title  of  the  drawing  should  be  followed  by  an  indication 
of  the  scale  of  the  drawing,  e.  g.  x  |  means  one-half  the 
natural  size,  x  5  means  five  times  natural  size. 

Dissection 

The  object  of  dissection  is  to  separate  the  various  organs 
or  parts  in  such  a  way  as  to  show  their  form  and  relation 
to  each  other.  It  consists  largely  in  removing  the  con- 
nective tissue  which  holds  the  parts  together. 

Fix  the  specimen  firmly  in  a  position  that  will  be  con- 
venient for  work,  usually  with  the  head  away  from  you. 
If  pins  are  used  stick  them  obliquely  into  the  wax  of  the 
dissecting  pan.  Large  specimens  should  be  moistened  from 
time  to  time  to  keep  from  drying,  and  small  animals  should 
be  dissected  under  water. 

Before   starting  a  dissection  study  the  specimen  care- 


22  GENERAL  BIOLOGY 

fully  and  note  where  the  cut  may  be  made  to  expose  the  part 
wanted  with  the  least  injury  to  the  surrounding  parts.  Do 
not  grasp  nerves  or  bloodvessels  with  the  forceps,  but  hold 
the  tissue  at  one  side  of  them.  Do  not  allow  scraps  to 
accumulate  on  the  specimen;  with  a  pipette  wash  away 
the  debris  which  gathers  on  the  specimen  under  water,  and 
change  the  water  frequently. 

Instruments  must  be  kept  clean  and  sharp  to  accomplish 
the  best  results,  therefore  do  not  use  scissors  or  scalpel  to 
cut  hard  objects  and  do  not  allow  the  instruments  to  be- 
come rusty. 

Clean  and  dry  the  instruments,  after  using,  and  smear 
them  with  a  little  oil  or  vaseline. 

The  scissors  are  used  almost  exclusively  when  cutting  is 
to  be  done.  Each  blade  of  the  scissors  holds  the  object  for 
the  other  blade,  whereas  the  scalpel  tends  to  push  out  of 
the  way  the  object  to  be  cut,  and  also  often  leads  to  the 
cutting  of  underlying  tissues  that  should  not  be  injured. 
While  cutting  with  one  hand,  whether  with  the  scissors  or 
scalpel,  always  use  the  forceps  in  the  other  to  steady  the 
object  and  to  hold  the  edge  of  the  cut. 

The  Microscope 

Since  the  compound  microscope  is  the  instrument  most 
indispensable  to  the  biological  student  some  knowledge  of 
its  construction  and  manipulation  should  precede  its  im- 
mediate application  to  the  work  in  which  it  is  used.  The 
following  study  of  its  parts  and  their  relations  may  there- 
fore be  made  in  the  order  indicated. 

1.  Parts,  (a)  The  base,  a  heavy  support  bearing  (6)  the 
column  to  which  is  fastened  (c)  the  stage,  a  horizontal  sup- 
port for  objects  to  be  examined.  In  the  center  of  the  stage 


INTRODUCTION  23 

is  an  opening  for  the  passage  of  light  by  which  an  object  is 
to  be  illuminated.  It  is  provided  with  clips  for  firmly 
holding  the  object  in  position  during  its  study.  Situated 
just  under  the  lower  side  of  the  stage  is  a  mechanism,  (d) 
the  diaphragm,  for  regulating  the  amount  of  light  admitted 
to  the  object.  Note  that  these  diaphragms  may  be  of 
different  types,  mere  disks  to  be  inserted  in  the  stage,  or  a 
circular  disk  to  be  rotated,  or  a  shutter-like  device  known 
as  the  iris  diaphragm,  (e)  Attached  to  a  movable  arm 
under  the  stage  is  the  mirror  by  which  light  is  reflected  through 
the  object  and  lens  to  the  eye  of  the  observer.  Note  that 
it  is  double,  having  on  one  side  a  plane,  and  on  the  other 
a  concave  surface;  the  latter  serves  to  concentrate  more 
light  upon  the  object,  and  should  be  used  chiefly  with  the 
high  power  lenses. 

Above  the  stage  is  (/)  the  tube  supported  on  the  arm  of 
the  microscope.  The  tube  is  a  means  of  attaching  the 
optical  parts,  i.  e.,  the  lenses,  of  which  there  are  several; 
those  at  the  upper  end  being  called  the  oculars  or  eye-pieces 
since  they  relate  directly  to  the  eye  of  the  observer;  those 
attached  to  the  lower  end  known  as  the  objectives,  since 
they  relate  to  the  object  under  observation.  The  wheel- 
like  parts  working  on  the  side  of  the  arm,  and  a  similar 
smaller  one  at  the  top  or  side,  have  to  do  with  focusing  to 
be  explained  later. 

2.  Adjustments. — These  refer  to  the  matter  of  so  relating 
the  mirror,  the  object  to  be  studied,  the  lenses  employed, 
the  amount  of  light  admitted,  that  clear  and  distinct  images 
are  afforded.  First  in  the  process  is  that  of  light,  and 
practice  will  be  required  in  order  to  learn  its  importance. 
This  will  involve  testing  the  effects  of  both  plane  and  con- 
cave mirrors,  the  use  of  the  diaphragm  in  regulating  the 
amount  of  light,  and  finally  that  adjustment  of  the  lenses 


24  GENERAL  BIOLOGY 

known  as  focusing.  In  the  last  of  these  operations  will  be 
involved  learning  the  uses  of  the  so-called  coarse  and  fine 
adjustments,  the  former  effected  by  means  of  the  rack  motion 
produced  by  the  large  milled  heads  at  the  side  of  the  arm, 
and  the  second  by  means  of  the  small  milled  head  at  the  top 
or  side.  Try  out  all  these  operations  in  a  general  way  and 
finally  under  the  directions  of  the  next  section. 

3.  Focusing. — The  object  to  be  examined  must  be  thin, 
since  the  light  must  pass  through  it.  The  object  is  placed 
on  a  glass  slide,  with  a  drop  of  water  or  other  liquid,  and 
covered  with  a  thin  glass  cover.  Place  the  slide  on  the  stage 
with  the  object  directly  over  the  center  of  the  opening. 
Move  the  low  power  objective  rather  close  to  the  slide  and, 
while  looking  into  the  eyepiece,  turn  the  coarse  adjustment 
so  as  to  raise  the  tube  until  the  object  comes  into  view, 
now  using  the  fine  adjustment  focus  carefully  until  the  image 
is  perfectly  sharp. 

The  high  power,  wyhen  in  focus,  is  so  close  to  the  cover 
glass  that  great  care  must  be  used  in  adjusting  it  or  it  may 
be  injured.  Turn  the  nose  piece  slowly  to  bring  this  ob- 
jective into  position,  taking  care  to  see  that  it  does  not 
touch  the  cover  glass.  If  it  swings  into  position  without 
striking,  a  slight  movement  of  the  fine  adjustment  will  usually 
bring  the  image  into  sharp  focus.  If  the  high  powrer  can- 
not be  swung  into  position  the  same  process  of  focusing 
must  be  used  as  for  the  low  power.  Always  focus  upward, 
since  to  do  the  contrary  may  result  in  the  lens  striking  the 
slide  to  the  injury  of  both  the  slide  and  the  lens. 

Practice  these  points  patiently  and  with  care  until  every 
phase  is  clearly  understood  and  easily  managed.  This 
practice  in  manipulation  will  be  time  wTell  spent,  since  later 
work  will  thereby  be  done  easily  and  skilfully. 


INTRODUCTION  25 

4.  Use  and  Care  of  the  Microscope. — Having  learned  the 
parts  and  adjustments  of  the  instrument  practice  their 
use  until  they  become  familiar.  This  is  especially  im- 
portant in  the  adjustments  relating  to  light.  Test  manip- 
ulation of  mirrors  and  diaphragms  until  able  to  obtain 
and  control  just  the  amount  and  quality  of  light  essential 
to  the  best  effects,  doing  so  with  eye  constantly  at  the  ocular. 
The  best  light  is  that  of  the  open  sky  (not  sunlight  direct) 
or  that  reflected  from  bright  clouds.  Artificial  light  may 
be  used  provided  a  screen  of  some  sort  be  interposed,  such 
as  a  bluish,  or  ground  glass.  Begin  every  study  with  the 
low  power,  nothing  is  gained  by  using  a  higher  power  than 
serves  the  end  in  view. 

To  avoid  eye  fatigue  while  using  the  microscope  practice 
looking  with  both  eyes  open,  which  after  a  little  practice 
is  not  especially  difficult.  If  not  easily  acquired,  an  artificial 
shade  or  screen  may  be  used  as  may  be  explained  by  the 
instructor. 

Proper  care  of  the  microscope  is  important  if  its  efficiency 
is  to  be  at  its  best.  Keep  every  part  clean,  do  not  allow 
water,  or  dirt,  or  chemicals,  to  remain  in  contact  with  any 
of  its  parts.  This  is  especially  important  for  the  lenses. 
Do  not  touch  the  lenses  with  the  naked  finger,  and  if  they 
should  appear  dirty  cleanse  with  lens  paper  furnished  by 
the  laboratory.  This  may  be  facilitated  by  breathing  on 
the  lens  and  then  gently  wiping  dry. 

Never  attempt  to  take  lenses  apart. 


THE  FROG. 

RANA  SP. 

FROGS  may  be  had  at  various  times  of  the  year,  and  are 
easily  kept  in  proper  aquaria,  so  arranged  that  the  animals 
have  range  from  water  to  dry  or  rocky  support,  provided 
care  is  taken  to  guard  against  serious  contamination  of  tank 
or  water.  They  may  be  secured  in  late  summer  or  fall,  or 
even  in  spring,  though  in  New  York  State  there  is  now  a 
closed  season  in  the  spring  as  for  other  game  animals.  In 
addition  to  living  specimens  kept  during  the  year  there 
should  also  be  an  ample  supply  of  preserved  material  for 
the  needs  of  classes.  If  specimens  are  to  be  injected  for 
study  of  the  blood  system  this  must  be  done  immediately 
after  killing  preparatory  to  preservation. 

In  the  neighborhood  of  larger  cities  frogs  may  often  be 
secured  through  fish  markets,  provided  attention  is  given 
to  the  subject  in  ample  time,  and  often  at  prices  much  lower 
than  those  charged  by  professional  supply  departments. 

I.  External  Characters. 

What  is  the  shape  of  the  body  as  a  whole?  Are  dorsal 
and  ventral  surfaces  well  marked?  How?  Note  the  di- 
vision of  the  animal  into  head,  trunk,  and  limbs.  Is  there 
a  neck  and  tail?  What  is  the  character  of  the  skin?  In 
the  living  animal  is  the  skin  moist  or  dry,  warm  or  cold? 
Are  there  scales  or  other  protective  structures  in  the  skin? 

1.  Head.— Note  its  triangular  shape.  Observe  the  follow- 
ing parts :  mouth,  nostrils,  eyes,  ear-drum  or  tympanic  mem- 


THE  FROG  27 

brane.     Do    the    eyes    have    lids?     How    many?    Which 
moves  in  the  living  frog?     Draw  the  head  from  the  side. 

2.  Trunk.— Note  the  shape  and  the  differences  in  the 
dorsal  and  ventral  sides. 

3.  Limbs.— Note  the  number  and  arrangement.    In  the 
hand.      How  many   digits   or  fingers?    The   hind  limb   is 
fore  limbs  the  following  divisions    occur:      arm,    forearm, 
divided  into  thigh,  leg,  and  foot.     How  many  digits?  -  How 
is  the  leg  adapted  for  swimming?     Compare  with  the  fore 
limb  in  length  and  number  of  digits.     Draw  both  fore  and 
hind  leg. 

4.  External  Apertures.— Note  the  position,  shape  and  size 
of  the  following:    mouth,  anus,  nostrils. 

II.  Mouth  Cavity. 

Open  the  mouth  to  its  full  extent,  cutting  the  corners  of 
the  jaw  if  necessary.  Are  there  lips?  Is  there  a  tongue? 
What  is  its  shape,  size  and  mode  of  attachment?  Where, 
are  the  teeth  found?  Teeth  on  the  jaw  bones  are  called 
maxillary  teeth,  those  on  the  roof  of  the  mouth  are  vomerine 
teeth.  Pass  a  bristle  through  the  outer  nostrils  and  observe 
the  inner  or  posterior  nostrils.  Where  are  they  found? 
Pierce  the  tympanic  membrane  and  pass  a  blunt  probe  into 
the,  ear;  in  the  mouth  cavity  the  place  where  the  probe 
appears  is  the  opening  of  the  Eustachian  tube. 

In  the  posterior  floor  of  the  mouth  just  at  the  end  of  the 
tongue  is  a  slit,  the  glottis,  opening  into  the  trachea  and 
lungs.  Its  margin  is  stiff  and  cartilaginous,  and  the  opening 
is  closed  except  when  air  is  passing.  The  esophagus  lies 
dorsal  to  the  glottis.  Compare  with  the  latter. 

Make  a  drawing  of  the  mouth  cavity,  showing  all  the 
points  referred  to. 


28     '  GENERAL  BIOLOGY 

m.  Internal  Anatomy. 

Fasten  the  frog  in  the  dissecting  pan  on  its  back,  and  slit 
the  skin  the  entire  length  of  the  body  in  the  median  line. 
Is  the  skin  loosely  or  closely  attached  to  the  body?  The 
spaces  that  are  found  beneath  the  skin  are  lymph  spaces. 
Laying  back  the  skin  observe  the  walls  of  the  abdomen, 
made  up  of  muscles.  Determine  the  points  of  attachment 
of  these  muscles.  In  what  directions  do  the  fibers  of  the 
muscles  extend  on  the  ventral  wall,  and  on  the  side  wall? 
The  ventral  muscles  are  the  straight  abdominal,  and  those 
of  the  side  walls  are  the  oblique  abdominal  muscles.  Also 
observe  the  group  of  pectoral  or  breast  muscles  in  the  region 
of  the  arm.  Is  this  one  muscle  or  a  group  of  muscles  ?  What 
is  the  probable  function  of  these  muscles? 

Draw  the  ventral  surface  of  the  frog,  showing  the  muscles 
just  studied.  If  time  permits,  the  muscles  of  one  of  the 
hind  legs  may  be  studied  and  a  drawing  made. 

Cut  through  the  body  wall,  taking  care  not  to  injure  the 
organs  lying  beneath.  Notice  that  the  internal  organs  lie 
in  a  large  cavity,  the  body  cavity  or  ccelom.  Pin  back  the 
flaps  and  observe  the  following  organs  which  are  exposed: 

1.  Heart.— In  the  median  line  beneath  the  pectoral  girdle. 
It  has  two  thin-walled  auricles  and  a  thicker-walled  ven- 
tricle, the  whole  being  enclosed  in  a  delicate  sac,  the  peri- 
cardium. If  the  heart  is  beating  record  the  order  of  the 
pulsations  of  the  different  chambers.  From  the  ventricle 
a  large  vessel,  the  truncus  arteriosus,  extends  obliquely  for- 
ward over  the  auricles.  On  the  dorsal  side  of  the  heart  is 
a  thin,  triangular  sac,  the  sinus  venosus,  into  which  the  blood 
comes  before  entering  the  heart.  Does  the  sinus  com- 
municate with  the  auricles  or  the  ventricle? 

Make  drawings  of  the  heart  to  show  these  points. 


THE  FROG  29 

2.  Liver.— A  large,  dark  red  mass,  dorsal  to  the  heart. 
What  is  its  size  and  shape?    Of  how  many  lobes  is  it  com- 
posed?   Between  the  lobes  is  the  bile  sac,  .or  gall  bladder. 
The  cystic  ducts  are  tubes  which  lead  from  the  liver  to  the 
bile  sac  and  the  bile  duct  extends  from  the  bile  sac  through 
the  pancreas  to  the  digestive  tube,  which  it  enters  about 
half  an  inch  posterior  to  the  stomach.    Turn  the  liver  for- 
ward and  trace  the  bile  duct  to  its  opening  into  the  intestine. 

Make  a  drawing  of  this  region. 

(If  the  specimen  is  a  female  take  up,  at  this  point,  the 
study  of  the  reproductive  organs.  Having  shown  their 
position,  size  and  structure  in  a  drawing,  remove  them  and 
study  further  the  other  organs  of  the  body  cavity.) 

3.  Lungs.— Two  thin-walled  sacs  dorsal  to  the  liver  and 
at  the  sides  of  the  esophagus.    Note  the  texture  pf  the  walls 
and  the  character  of  the  lining.    The  lungs  may  be  expanded 
by  blowing  air  into  them. 

4.  Stomach.— Note  the  shape,   size  and  position.     How7 
is  the  stomach  held  in  place?     Slit  the  stomach  longitudi- 
nally, and  determine  the  character  of  its  walls  and  its  lining. 

5.  Intestine.— Is  it  straight  or  coiled?    How  is  it  held  in 
position?    Compare  the  walls  with  those  of  the  stomach. 
Near  the  posterior  end  note  an  enlargement,  the  large  intestine. 

6.  Pancreas.— A  pale  mass  lying  in  the  loop  made  by 
stomach  and  intestine.    Show  its  position  in  the  drawing 
made  of  the  liver. 

7.  Spleen.— A  small  round  body  lying  in  the  posterior 
part  of  the  body.    Does  it  appear  to  be  joined  to,  or  connected 
with  any  other  organ? 

8.  Bladder.— A  thin  walled  sac  in  the  extreme  posterior 
part  of  the  body  cavity.    What  is  its  shape?    With  what 
organs  does  it  communicate? 

Make  a  drawing  to  show  the  organs  so  far  studied. 


30  GENERAL  BIOLOGY 

9.  Ovaries.— Found  in  the  female  and  composed  of  masses 
of  eggs,  their  size  depending  upon  the  maturity  of  the  animal, 
and  the  time  of  year.    If  the  ovaries  are  mature  they  may 
almost  completely  fill  the  body  cavity  crowding  all  the  other 
organs  that  are  in  the  cavity.    If  the  animal  is  immature 
the  small  ovaries  will  be  found  near  the  dorsal  part  of  the 
body  cavity  hidden  by  the  digestive  organs.    Long  con- 
voluted tubes  along  the  dorsal  wall  of  the  body  cavity  are 
the  oviducts.    Anteriorly  these  are  held  in  place  against 
the  esophagus,  and  open  into  the  coelom  by  a  funnel-shaped 
mouth.    Near  the  posterior  end  each  oviduct  enlarges  to 
form  a  sort  of  bladder,  called  the  uterus. 

Fastened  near  the  anterior  end  of  the  ovaries  are  slender 
yellowish  fat  bodies. 

10.  Testes.— These  organs,  the  male  reproductive  organs, 
are  oval  yellowish  bodies  near  the  dorsal  body  wall.    Usually 
connected  to  them  are  slender  yellowish  fat  bodies.     Ducts 
from  the  testes  pass   into  the   kidneys  and  communicate 
with  the  urinary  duct  or  ureter.    The  ureter,   therefore, 
functions  as  a  common  urino-genital  duct.    Rudiments  of 
oviducts  may  occasionally  be  present  along  the  sides  of  the 
kidneys. 

11.  Kidneys.— To   study   the   kidneys   and   their   ducts, 
remove  the  muscle  and  a  portion  of  the  bony  pelvic  girdle 
which  lie  ventral  to  the  intestine  and  cloaca.    Place  the 
animal  under  water  and  displace  the  other  organs  to  expose 
the  kidneys,  a  pair  of  elongated  reddish  organs  situated 
close  to  the  vertebral  column.    A  small  tube,  the  ureter, 
extends  from  the  posterior  end  of  each  kidney  to  the  cloaca. 
On  the  ventral  side  of  each  kidney  is  a  narrow  yellowish 
line,  the  adrenal  body,  a  gland  whose  secretion  is  poured 
into  the  blood. 


THE  FROG  31 

12.  Cloaca.— The  cloaca  is  a  continuation  of  the  large 
intestine,  and  opens  to  the  outside  on  the  dorsal  side  of  the 
animal.  Expose  the  cloaca  and  note  the  connection  of 
the  bladder,  ureters,  and  oviducts  with  it. 

A  diagrammatic  drawing  made  from  the  side  will  show 
the  relations  of  these  ducts  to  each  other  and  to  the  cloaca; 
or  a  drawing  on  a  large  scale,  from  the  ventral  side  will  be 
satisfactory  if  some  parts  are  slightly  displaced. 

Observe  the  peritoneum,  a  pigmented  membrane  which 
lines  the  ccelom.  This  also  covers  the  organs,  and  makes 
up  the  mesenteries  which  hold  the  various  organs  in  position. 

IV.  Circulatory  System. 

This  system  must  be  worked  out  from  specimens  whose 
vessels  have  been  filled  with  a  colored  injection  mass.  Such 
an  injection  expands  the  bloodvessels  and  causes  them  to 
stand  out  clearly  from  surrounding  tissues  and  organs.  If 
an  injected  animal  is  not  used  only  a  few  of  the  larger  vessels 
will  be  found,  and  these  can  be  followed  for  only  a  short 
distance 

1.  Heart.— Observe  again  the  shape  and  position  of  the 
heart,  and  the  chambers  of  which  it  is  composed. 

2.  Arteries.— Leading  from  the  ventricle  is  a  single  large 
artery,  the  truncus  arteriosus,  which  divides  into  tvtp  parts, 
one  passing  to  the  right,  and  the  other  to  the  left.    Each 
of  these   subdivides    into  three  arteries  called  the  aortic 
arches.    The  most  anterior  of  these  is  the  carotid  arch,  which 
supplies  blood  to  the  head.    Following  this  is  the  systemic 
arch  which,  with  its  branches,  carries  blood  to  the  trunk 
and  appendages.    The  most  posterior  of  the  three  arches  is 
the  pulmo-cutaneous  which  conducts  blood  from  the  heart 
to  the  lungs  and  skin. 


32  GENERAL  BIOLOGY 

From  each  of  these  large  vessels  arise  a  number  of  smaller 
arteries;  their  origin  should  be  determined,  and.  their  dis- 
tribution carefully  followed. 

A.  Carotid  Arch.    This  arch  divides  into  two  arteries: 
(a)    External  carotid  or  lingual  which  supplies  blood  to 

the  tongue  and  muscles  of  the  lower  jaw. 
(6)    Internal  carotid,  which  passes   around  the  lower  jaw 
to  the  roof  of  the  mouth,  the  orbit  of  the  eye,  and  the 
brain. 

At  the  junction  o£  these  two  arteries  is  a  swelling, 
the  carotid  gland. 

B.  Pulmo-cutaneous   Arch.     This,   the  posterior   of   the 
three  arches,  divides  into  twro  arteries : 

(a)  The  pulmonary  extends  to  the  lungs,  in  which  it 
divides  into  several  smaller  vessels. 

(6)  The  cutaneous  extends  anteriorly  to  the  shoulder 
wrhere  it  passes  dorsally,  and,  emerging  behind  the 
ear,  is  distributed  over  the  skin  of  the  back  and  side. 

C.  The   middle   arch,    the   systemic,    extends   dorsally, 
passes  around  the  esophagus,  and  the  two  sides  of 
the  arch  unite  into  a  single  vessel,  the  dorsal  aorta, 
which  proceeds  posteriorly  along  the  spinal  column. 
From  each  side  of  the  arch  several  arteries  arise. 

(a) .  The  subclavian,  a  large  artery  which  goes  to  the 
shoulder,  w-ill  easily  be  found;  it  continues  into  the 
arm  where  it  is  called  the  brachial. 

(6)  The  occipito-vertebral  arises  just  anterior  to  the  sub- 
clavian, passes  dorsally  through  the  body  wall  and 
divides  into  two  arteries.  Branches  from  this  artery 
may  extend  into  the  esophagus. 

(c)  Laryngeal.— Along  the  systemic  arch  between  the 
occipito-vertebral  artery  and  the  heart  is  a  small 
artery,  the  laryngeal,  which  goes  to  the  trachea  and 
larynx. 


THE  FROG  33 

(rf)   Esophageal.  — This   artery  arises   from  the  systemic 

arch  posterior  to  the  subclavian,   about  half  way 

between  it  and  the  dorsal  aorta.    As  a  rule  it  comes 

only  from  the  arch  of  the  left  side. 
(e)    Dorsal  Aorta.— If  the  stomach  is  pulled  aside  this 

artery  will  be  found  along  the  spinal  column;    it  is 

formed  by  the  union  of  the  systemic  arches  of  the 

right  and  left  sides. 

Branching  from  the  dorsal  aorta  are : 

(I)  Coeliaco-mesenteric.—  This  large  artery  extending 
to  stomach,  intestine,  pancreas,  liver,  and  spleen 
comes  from  the  dorsal  aorta  just  posterior  to 
the  union  of  the  two  sides  of  the  systemic  arch; 
but  the  blood  is  derived  almost  entirely  from  the 
left  side  of  the  arch.  The  coeliac  artery  supplies 
the  stomach,  the  mesenteric  the  intestine,  the 
splenic  the  spleen. 

(II)  Urino-genital  and  lumbar  arteries  arise  from  the 
ventral  side  of  the  dorsal  aorta  in  pairs,  and 
extend  to  the  kidneys,  reproductive  organs,  fat 
bodies,  and  dorsal  body  wall. 

(Ill)     Near   the  extreme   posterior  end  of  the  dorsal 
aorta  a  small  posterior  mesenteric  artery  passes 
into  the  rectum. 
(/)    Common  iliac  arteries  are  formed  by  the  division  of 

the  dorsal  aorta;   they  supply  blood  to  the  hind  legs. 

(J)  A  short  distance  from  its  origin  each  common 
iliac  gives  off,  on  the  outer  side,  one  or  more 
epigastric  arteries  which  extend  to  the  ventral 
abdominal  wall. 

(II)  Slightly  posterior  to  the  epigastric  a  small  artery, 
the  recto-vesical,  comes  out  on  the  inner  side  of 
the  iliac  and  supplies  blood  to  the  bladder,  cloaca, 
and  pelvic  muscles. 


34  GENERAL  BIOLOGY 

(g)  The  sciatic  artery  is  the  continuation  of  the  iliac  artery 
in  the  leg.  Soon  after  entering  the  leg  the  sciatic 
gives  off  a  large  branch,  the  femoral  artery,  which 
supplies  blood  to  the  thigh  muscles.  At  the  knee 
the  sciatic  divides  into  two  chief  branches,  the  tibial 
extending  along  the  front  of  the  leg  into  the  foot,  and 
the  peroneal  which  passes  along  the  back  of  the  leg 
into  the  calf  muscles. 

Make  a  large  drawing  of  the  heart  and  arterial 
system,  carefully  showing  the  origin  and  distribution 
of  the  vessels  studied. 

3.  Veins.— While  the  arteries  have  been  under  investi- 
gation it  will  have  been  noticed  that  there  were  other  vessels, 
not  injected,  running  parallel  with  the  arteries.  These  were 
some  of  the  larger  veins  of  the  body.  The  veins  make  up  a 
system  for  the  return  of  the  blood  to  the  heart,  but  their 
further  study  will  not  be  attempted  here. 

Before  leaving  the  study  of  the  circulatory  system  one 
should  see  the  circulation  of  blood  in  a  living  frog.  This 
may  easily  be  done  by  examining  with  a  microscope  the 
thin  web  in  the  foot  of  an  anesthetized  animal. 

V.  Nervous  System. 

The  nervous  system  consists  of  three  general  divisions; 
the  central,  composed  of  the  brain  and  spinal  cord;  the 
peripheral,  which  includes  the  nerves  connecting  the  central 
system  with  sense  organs  and  muscles;  the  sympathetic,  a 
series  of  nerves  extending  to  the  internal  organs. 

1.  The  Central  System.— Place  the  frog  dorsal  side  upper- 
most and  slit  the  skin  along  the  median  line  from  the  snout 
to  the  anus.  Lift  up  the  cut  edges  and  notice  the  pairs  of 
delicate  thread-like  nerves  which  run  through  the  muscles 


THE  FROG  35 

of  the  body  wall  to  the  skin.  Next  remove  the  skin  of  the 
body,  the  roof  of  the  cranial  cavity,  the  muscles  of  the  back, 
and  with  sharp  pointed  scissors  cut  away  the  arches  of  the 
vertebrae.  This  will  expose  the  brain  and  spinal  cord  which 
will  be  found  to  be  covered  with  a  delicate  blackish  membrane, 
the  pia  mater.  In  addition  to  this  inner  covering  there  is 
an  outer  one,  the  dura  mater,  which  lies  close  to  the  skull 
and  vertebrae,  and  has  been  removed  with  the  bone. 

The  following  parts  may  now  be  identified,  beginning 
with  the  anterior  end : 

(a)  Olfactory  Lobes.— These  are  at  the  extreme  anterior 
end  of  the  brain.  They  are  not  distinct  lobes  but 
are  separated  by  a  shallow  groove  from  the  rest  of 
the  brain.  Are  the  two  lobes  separate  or  fused? 
Olfactory  nerves  pass  forward  from  these  lobes  to 
the  nostrils. 

(6)  Cerebral  Hemispheres. —Two  large  ovoid  bodies  im- 
mediately posterior  to  the  olfactory  lobes. 

(c)  Thalamencephalon,    a    narrow,      cylindrical     portion 
connecting  the  cerebral  hemispheres  with  the  optic 
lobes.    Upon   it,   occupying   a   median   position,   is 
a  small  body,  the  pineal  gland. 

(d)  Optic    Lobes,     posterior    to    the    thalamencephalon. 
What  is  the  size  and  shape  of  these  parts  as  com- 
pared with  the  cerebral  hemispheres? 

(e)  The    Cerebellum  is  a  small  transverse  fold  posterior 
to  the  optic  lobes. 

(/)  Medulla  Oblongata,  following  the  cerebellum.  In  it  is 
a  triangular  cavity,  the  fourth  ventricle. 

(</)  Spinal  Cord.— The  medulla  tapers  gradually  into  the 
cord  without  any  sharp  demarcation.  Is  the  cord 
as  long  as  the  body?  Is  it  of  equal  width  through- 
out its  length?  If  not,  in  what  regions  is  it  widest? 


36  GENERAL  BIOLOGY 

A  swelling  in  the  region  of  the  arm  would  constitute  a 

brachial  enlargement,   and  one  near  the  legs  a  sacral 

or  lumbar  enlargement.    How  does  the  cord  terminate  ? 

Make  a  large  drawing  of  the  brain  and  spinal  cord  from 

the  dorsal  side.    Use  care  in  getting  the  dimensions  and 

proportions  accurate,  measuring  the  parts  with  a  rule  if 

necessary. 

Carefully  remove  the  brain  and  cord  from  the  body, 

place  in  a  watch  glass  of  water,  and  construct  an  accurate 

drawing  of  the  ventral  side  of  the  brain.    In  addition  to 

the  parts  already  observed  the  following  should  be  identified: 

(h)    Optic  Chiasma.— Formed  by  the  crossing  of  the  optic 

nerves  as  they  leave  the  optic  lobes. 
(i)    Infundibulum.—  A  small  shield-shaped  body  posterior 

to  the  optic  chiasma. 

(j)    Pituitary  Body.— This  lies  in  a  little  pocket  of  bone  in 
•   the  floor  of  the  skull.     It  is  usually  torn  from  its 
attachment  to  the  infundibulum  when  the  brain  is 
removed  from  the  cranial  cavity. 

2.  The  Sympathetic  System.— This  is  best  seen  by  placing 
the  animal  ventral  side  up,  moving  the  viscera  to  one  side 
and  looking  for  a  very  delicate  thread-like  nerve,  the  sym- 
pathetic nerve,  which  runs  along  one  side  of  the  dorsal  aorta; 
a  similar  nerve  is  present  in  the  same  position  on  the  other 
side.  When  these  are  found  the  organs  of  the  body  and  the 
lower  jaw  should  be  removed,  but  the  dorsal  aorta  left  in 
place.  Place  the  animal  under  water  and  lift  the  dorsal 
aorta  to  find  the  sympathetic  nerves,  their  ganglia  and  con- 
nections with  the  spinal  nerves.  Observe  carefully  the 
relation  of  sympathetic  and  spinal  nerves,  the  position  and 
number  of  sympathetic  ganglia,  and  the  delicate  nerves  con- 
necting spinal  and  sympathetic  nerves. 

A  single  drawing  should  be  made  to  show  the  sympathetic 
and  peripheral  systems. 


THE  FROG  37 

3.  The  Peripheral  System.— This  is  composed  of  the  nerves 
which  come  from  the  brain  and  spinal  cord;  the  former  are 
called  cranial  nerves,  the  later  spinal  nerves.  There  are  ten 
pairs  of  cranial  nerves,  but  on  account  of  their  close  relation 
to  the  bone  of  the  skull  their  origin  and  distribution  will  not 
be  worked  out.  If  possible  examine  a  demonstration  prep- 
aration showing  these  nerves. 

The  spinal  nerves  come  out  in  pairs,  and  each  single  nerve 

arises  from  the  cord  by  a  dorsal  and  a  ventral  root.     Since 

these  roots  pass  through  the  bone  of  the  vertebral  column 

their  origin  is  difficult  to  determine,  but  the  spinal  nerves 

themselves  may  easily  be  found  along  the  dorsal  wall  of  the 

body  cavity.     Determine  how  many  of  these  nerves  there 

are,  and  trace  their  course  and  distribution.    Give  especial 

attention  to  networks  or  fusions  of  nerves  called  plexuses: 

(a)    The  brachial,  in  the  region  of  the  fore  limb.    Of  how 

many  nerves  is  the  plexus  composed?    Is  the  fusion 

of  these  nerves  complete?    Trace  a  large  nerve,  the 

brachial,  into  the  arm. 

(6)    The  sciatic  or  lumbar  plexus,  is  in  the  posterior  part 
of  the  body  anterior  to  the  place  where  the  legs  are 
attached.    Of  how  many  nerves  is  the  plexus  com- 
posed?   What  is  the  nature   and  the  extent  of  the 
union?    Trace  a  large  nerve,  the  sciatic,  into  the  leg. 
Follow  it  in  its  course  through  the  leg  and  foot. 
Construct  a  large  drawing  showing  the  spinal  nerves,  and 
the  sympathetic  system  so  far  as  it  has  been  studied. 

VI.  Sections  of  the  Body. 

Having  studied  the  organs  and  the  parts  of  the  body 
thoroughly,  we  should  have  a  good  idea  of  the  relations  of 
one  part  to  another.  Make  a  drawing  of  an  ideal  cross- 

64186 


38  GENERAL  BIOLOGY 

section  of  the  body  of  the  frog  showing  all  the  organs  and 
parts  in  their  proper  relation  and  proportion. 

VH.  Microscopic  Anatomy.     (Histology.) 

This  involves  the  study  of  the  tissues  and  cells  of  which 
the  various  organs  are  composed.  It  will  be  found  that 
there  are  only  a  few  kinds  of  fundamental  tissues  and  these 
are  repeated  over  and  over  again  in  the  various  organs.  The 
relations  of  shape  and  position  may  differ  somewhat  in 
different  places,  but  the  tissues  have  the  same  general  ap- 
pearance and  function  wherever  they  are  found. 

1.  Tissues. 

(a)  Blood.— Mount  a  drop  of  the  blood  of  a  frog  on  a  slide, 
and  cover  with  a  cover  glass.    Observe  the  colorless 
fluid  or  plasma  in  which  are  floating  the  corpuscles 
or  blood  cells.   How  many  kinds  of  cells  do  you  find? 
Observe  their  shape,  color,  relative  size,  and  compar- 
ative numbers.     Are  the  cells  nucleated?    If  the  slide 
is   placed  on  a  warm  stage  it  may  be  possible  to 
demonstrate  the  movement  of  the  white  corpuscles. 
Draw. 

(b)  Epithelium.— Epithelial  tissues  are  those  which  cover' 
the  free  surfaces  of  the  body  or  line  cavities.    The 
outer  skin  and  the  lining  of  the  digestive  tube  are 
examples.    Epithelium  is  of  different  kinds  according 
to  the  shape,  structure  and  arrangement  of  the  cells. 
(I)    Squamous  or  Scaly.— Examine  the  epidermis  of 

the  frog.  What  is  the  form  of  the  cells?  Are 
nuclei  present?  Do  the  cells  form  a  layer?  Do 
they  overlap  at  the  edges?  If  possible  examine 
sections  made  vertically  through  the  entire  skin. 
In  these  sections  only  the  outer  layers  of  cells 
make  up  the  epithelium.  Draw. 


THE  FROG  39 

(II)  Columnar.— Examine  prepared  slides  which  show 
sections  through  the  intestine  of  the  frog.  What 
is  the  form  of  the  cells  lining  the  cavity?  How 
are  they  placed?  What  is  the  position  of  the 
nuclei  in  the  cells?  Goblet  cells,  which  contain 
secretions  of  mucus,  are  often  found  in  the 
epithelium.  Draw. 

(Ill)  Ciliated.— Examine  the  cells  scraped  from  the 
roof  of  the  mouth  of  a  freshly  killed  frog.  Com- 
pare the  cells  with  those  of  squamous  and  colum- 
nar epithelium  in  all  points.  In  what  are  they 
alike?  In  what  different?  Can  you  see  the 
movement  of  the  cilia?  Where  on  the  cells  are 
the  cilia  located?  Draw. 

(c)  Cartilage.— Examine  prepared  slides  of    cartilage,  or 
make  a  slide  of  fresh  cartilage  from  the  frog.    Get  a 
very  thin  piece  and  observe  the  transparent  matrix 
in  which  are  embedded  the  cartilage  cells.    Note 
the  shape  and  the  size  of  the  cells  and  the  manner  in 
which  they  are  grouped  together.    How  does  the 
cartilage  differ  in  appearance  from  the  other  tissues? 
Are  the  cells  nucleated  ?     Do  you  find  cells  with  more 
than    one    nucleus?    Explain.    To    what   does    the 
matrix  correspond  in  the  other  tissues?     Draw. 

(d)  Muscle. 

(I)  Striated.— The  striated  (voluntary)  muscles  are 
those  that  are  under  the  control  of  the  will. 
Examine  the  muscle  of  the  leg  of  the  frog,  by 
teasing  it  in  salt  solution.  The  fibers  should  be 
well  pulled  apart.  What  is  the  shape  of  the 
fibers?  Do  they  tend  to  separate  into  smaller 
fibrillae?  Is  there  anything  that  suggests  the 
name  "striated"  muscle?  If  nuclei  are  present 
where  in  the  fiber  are  they  located?  Draw. 


40  GENERAL  BIOLOGY 

(II)  Smooth  or  unstriated  muscles. —These  are  muscles 
which  are  automatic  in  action,  or  at  least  not 
under  conscious  control.  The  muscles  of  the 
intestines,  the  bladder,  etc.,  are  examples.  A 
piece  of  muscle  from  the  stomach  when  teased 
should  show  the  fibers.  Observe  the  shape, 
arrangement,  and  nuclei  of  the  fibers.  Draw7. 
(e)  Nerve  Tissue. 

(I)  Fibers. — Tease  the  sciatic,  or  other  large  nerve, 
in  salt  solution.  In  a  single  fiber  look  for  a 
place  where  it  is  torn  or  crushed  and  identify 
the  delicate  sheath  on  the  outside.  Inside  this 
is  the  thicker  medullary  sheath.  Making  up 
the  center  is  the  axis  cylinder,  axone,  or  nerve 
proper.  Draw. 

(II)  Cells.— Remove  one  of  the  spinal  ganglia  and 
tease  in  a  drop  of  salt  solution  containing  some 
stain,  or  study  prepared  slides  showing  the 
nerve  cells.  Look  for  large  cells  and  note  the 
relation  of  the  cells  to  the  fibers.  Is  there  a 
nucleus  in  the  cell?  Draw. 

2.  Organs.— Having  studied  several  of  the  fundamental 
tissues  one  should  be  able  to  recognize  them  in  organs.  In 
the  following  study  observe  what  tissues  are  present  and 
how  they  are  arranged : 

(a)  Spinal  Cord.— In  prepared  slides  of  sections  of  the 
spinal  cord  note  the  following  points:  shape,  size, 
surrounding  membrane  (pia  mater),  nerve  roots,  dorsal 
fissure,  ventral  fissure,  central  canal,  position  of  the 
white  matter,  shape  and  position  of  the  gray  matter. 
In  the  white  matter  will  be  found  nerve  fibers,  con- 
nective tissue,  bloodvessels  and  corpuscles.  In  the 
gray  matter  the  nerve  cells  will  be  rather  prominent. 


THE  FROG  41 

Make  an  outline  drawing  four  inches  in  diameter  showing 
the  relative  position  and  proportion  of  these  parts.  Arrange 
the  drawing  with  the  dorsal  side  of  the  cord  toward  the  top 
of  the  page.  Fill  in  with  care  some  of  the  details  of  structure 
observed. 

(6)  Stomach.— With  the  low  power  observe  the  four 
layers  of  the  wall,  as  follows,  from  without  inward: 
(I)  Serosa  or  Peritoneum.— (This  is  very  delicate 

and  may  be  lacking.) 
(II)  Muscular  coat,  consisting  of 

(1)  an  outer  longitudinal  layer.    Note  the 
shape  of  the  cells.   Do  all  contain  nuclei ? 
How  do  you  account  for  this? 

(2)  an  inner  circular  layer.    What  is  the 
shape  of  the  cells?    Are  nuclei  present? 
What  is  the  relative  thickness  of  the  two 
layers? 

(III)  Submucosa.  —  Made    up    chiefly    of    connective 
tissue    and    bloodvessels.      Note    the    general 
character  of  the  tissue  and  the  staining  proper- 
ties. 

(IV)  Mucosa   or  Mucous  Membrane.— This  is  marked 
off  from  the  submucosa  by  a  narrow  band  of 
muscle  cells  (the  muscularis  mucosae).     The  sur- 
face is  covered  with   columnar  epithelium  which 
dips  down  to  form  numerous  pits  into  which  the 
gastric    glands    empty.    The    glands    are    sur- 
rounded by  connective  tissue. 

Make  a  drawing  three  inches  in  diameter  of  a  segment 
of  the  stomach  wall  as  seen  under  low  power. 

Under  high  power  study  a  portion  of  the  mucosa  and  note 
the  following  points:  shape  of  the  gastric  glands;  general 
character  of  the  epithelium  lining  the  pits,  the  shape  of  the 
cells  and  the  position  of  the  nuclei. 


42  GENERAL  BIOLOGY 

Make  a  drawing  of  a  gastric  pit  and  of  the  glands  empty- 
ing into  it,  as  seen  with  the  high  power. 

Vm.  Embryology. 

It  will  be  found  necessary  to  have  a  complete  series  of 
eggs  and  tadpoles  preserved  in  formalin,  especially  in  large 
classes.  It  is  also  desirable  to  have  the  living  material  at 
hand  when  undertaking  this  study. 

1.  The  Egg.— Examine  the  eggs  in  a  mass,  also  compare 
the  masses  of  the  toad  and  other  amphibia.     How  thick  is 
the  surrounding  jelly?    Distinguish  in  it  three  layers,  wTith 
concentric  layers  in  them.  What  is  the  color  of  the  egg? 
The  darker  side  of  the  egg  is  the  animal  or  protoplasmic  pole, 
the  side  opposite  is  the  yolk  or  vegetative  pole. 

Make  a  drawing  of  the  egg  and  its  envelopes,  also  draw 
each  of  the  following  stages  as  studied. 

2.  Early   Cleavage    Stages.— What  evidence  do  you  find 
that  the  egg  differs  from  the  ones  previously  studied?     Find 
one  with  a  single  groove  surrounding  it.     In  what  direction 
does  the  groove  extend?    Are  the  resulting  parts  equal? 
Find  an  egg  with  a  second  groove  at  right  angles  to  the  first. 
The  first  one  gives  the  two-cell  stage,  the  second  one  the 
four-cell   stage.    Are  the   cells   equal   in   size?    The  third 
groove  passes  in  a  horizontal  or  equatorial  direction.     How 
many  cells  result  ?    What  is  their  relative  size  ? 

3.  Later  Cleavage  Stages.— Study  eggs  in  the  sixteen-cell, 
and  thirty  two-cell  stages.    How  are  these  stages  produced 
from  the  earlier  stages?    Are  the  cells  equal  in  size?    Ex- 
amine both  poles  of  the  eggs  and  explain  the  differences 
found.    Does  the  relative  size  of  the  pigmented  and  un- 
pigmented  areas  remain  unchanged  in  later  cleavage  stages? 
How  is  this  to  be  explained? 


THE  FROG  43 

4.  Blastopore.—  The  pigmented  cells  divide  more  rapidly 
than  the  white  cells  and  come  to  grow  over  the  latter;    at 
the  same  time  the  pigmented  cells  become  infolded  and  grow 
into  the  egg  itself.    This  continues  until  but  a  small  mass  of 
white  cells  can  be  seen.    The  term  blastopore  is  applied  to 
the  opening,  and  the  mass  of  white  cells  is  spoken  of  as  the 
yolk  plug.     Later  the  blastopore  closes  and  the  yolk  plug 
is  forced  inside  the  egg. 

5.  Neural  Groove.— On  what  is  to  become  the  dorsal  side 
of  the  body  will  be  found  an  open  groove  with  slightly 
elevated  margins.    How  far  does  it  extend?    Is.  it  open 
throughout  its  length?    Examine  several  specimens.    What 
distinguishes  the  part  which  is  to  form  the  brain  from  that 
which  will  produce  the  spinal  cord?     The  margins  grow 
together  to  form  a  tube  and  this  subsequently  develops  into 
the  brain  and  spinal  cord.    How  does  the  shape  of  the 
embryo  compare  with  the  earlier  stages?    In  eggs  which 
have  elongated,   is  there  any  marked  difference  between 
dorsal  and  ventral,  anterior  and  posterior? 

6.  Gill  Stage.— In  a  tadpole  just  hatched  observe  the  be- 
ginning of  the  formation  of  head,  body  and  tail.    There  is  no 
mouth  yet  present,  but  on  the  ventral  side  of  the  head  are 
suckers  by  which  the  tadpole  adheres  temporarily  to    some 
support.     Nostrils  and  eyes  are  beginning  to  form,  and  gill 
buds  indicate  the  position  of  future  gills.    In  a  somewhat 
later  stage  finger-like  gills  are  produced  upon  the  sides  of 
the  head.    At  such  a  period  mouth,  eyes,  nostrils  and  tail 
are  well  formed,  and  the  internal  organs  are  undergoing 
their  development. 

7.  Tadpole.— Distinguish   head,    body    and    tail    regions. 
What  has  become  of  the  external  gills?     The  fold  of  skin 
covering  the  internal  gills  is  the  operculum  and  the  opening 
to  the  gill  chamber  is  the  spiracle.     On  which  side  is  the 


44  GENERAL  BIOLOGY 

spiracle  found?  At  this  stage  the  eye,  mouth,  nostrils  and 
teeth  are  well  developed.  Also  on  the  ventral  surface  the 
heart,  internal  gills,  and  coiled  intestine  will  show  through 
the  body  wall. 

8.  Metamorphosis.— The  tadpole  or  fish-like  stage  con- 
tinues for  some  time  (it  may  be  a  year  or  two  in  frogs)  be- 
fore a  metamorphosis  into  the  adult  form  begins.  This 
metamorphosis  is  first  shown  by  the  formation  of  the  hind 
legs.  Carefully  study  a  tadpole  with  the  hind  legs  present 
and  determine  the  character  of  sense  organs  and  other  ex- 
ternal features.  The  forelegs  start  their  formation  within 
the  gill  chamber  and  are  not  apparent  externally  until 
they  become  rather  large,  when  they  break  through  the 
skin  covering  the  gills.  In  a  specimen  with  both  fore  and 
hind  legs  observe  the  changes  in  form  of  the  body  and  head. 
As  the  legs  increase  in  size  what  becomes  of  the  tail? 

Dissect  the  ventral  body  wall  from  a  large  tadpole  with- 
out legs,  and  also  from  one  with  both  pairs  of  legs  present. 
Determine  what  changes  are  taking  place  in  the  internal 
organs  during  this  time.  When  the  tail  is  finally  absorbed 
and  the  toad  or  frog  leaves  the  water,  the  animals  are  like 
adults  except  for  the  reproductive  organs,  which  require 
a  considerable  time  for  their  perfect  development. 


ORGANS,  TISSUES  AND  CELLS. 

THE  term  organism,  as  used  in  biology,  designates  in 
general  an  individual  animal  or  plant,  and  implies  that  they 
are  composed  of  organs.  For  example,  the  ears,  eyes,  legs 
feet,  of  a  dog  are  familiarly  known  as  organs;  and  the  same 
is  true  of  such  internal  structures  as  stomach  and  liver.  It 
is  perhaps  not  so  well  known  that  organs  are  likewise 
complex  structures  made  up  of  simpler  components,  and 
as  in  general  these  are  composed  of  a  network  of  similar 
elements  they  are  usually  spoken  of  as  tissues.  To  demon- 
strate the  organic  structure  of  a  frog  it  is  only  necessary  to 
critically  observe  its  external  features,  or  perhaps  dissect 
and  lay  open  its  interior.  To  demonstrate  that  organs  are 
composed  of  tissues  will  require  the  use  of  the  microscope, 
and  in  most  cases  some  means  of  dissecting  and  preparing 
them  for  study.  This  phase  of  biology  is  known  as  micro- 
scopic anatomy,  or  histology.  Finally,  such  a  study  will 
reveal  the  fact  that  a  given  tissue  is  composed  of  still  more 
elemental  .structures  which  are  called  cells.  The  following 
outline  of  laboratory  study  will  afford  a  direct  introduction 
to  these  phases  of  our  subject. 

1.  Mount  in  water  a  small  fragment  of  frog  epidermis, 
and  examine  with  the  high  power.    Make  a  careful  drawing 
of  a  group  of  cells,  showing  cell  walls,  and  nuclei. 

2.  Strip  the  epidermis  from  the  upper  surface  of  the  leaf 
of  Tradescantia,  mount  in  water  and  examine.    Compare 
the  shape,  size,  and  general  appearance  of  the  cells  with 
those  of  the  animal  epidermis.    Make  a  drawing  of  a  group 
of  cells. 

3.  With  a  razor  cut  very  thin  transverse  and  longitudinal 


46  GENERAL  BIOLOGY 

sections  of  the  stem  of  Tradescantia,  of  geranium,  begonia, 
or  other  plants,  mount  these  in  water  and  examine.  In  the 
cells  near  the  center  of  the  stem  note  the  shape,  arrange- 
ment, and  cell  contents.  Look  especially  for  crystals  in 
these  cells.  The  presence  of  crystals  in  the  cells  indicates 
the  presence  of  what  kind  of  material? 

4.  Cut  very  thin  sections  of  a  potato  tuber  just  beneath 
the  skin.    Mount  in  water,  study  and  make  drawings  of 
the  cells  and  their  contents.     Remove  the  cover  glass,  add 
a  drop  of  dilute  iodine  solution  and  allow  it  to  remain  for  a 
few  minutes.    Wash  off  the  iodine,  replace  the  cover  glass 
and  examine  the  section  again.     Since  the  iodine  solution 
has  the  property  of  turning  starch  blue  what  do  you  con- 
clude as  to  the  cell  contents  in  this  case? 

5.  Stems  of  other  plants  may  be  sectioned  and  treated 
in  the  same  manner,  and  an  idea  obtained  as  to  the  abun- 
dance of  starch  and  its  position  in  the  plant.     What  is  the 
use  of  this  starch?    What  explanation  can  you  give  as  to 
the  differing  amounts  of  starch  and  of  the  different  places 
of  storing  it  in  the  plants  examined? 

6.  Examine  cartilage  from  a  frog  or  other  animal  and 
make  drawings  showing  the  cells  and  the  intercellular  sub- 
stance.   Mount  a  drop  of  blood  from  the  frog  and  examine 
with  the  high  power,  draw  the  various  kinds  of  cells  found 
therein.    If  possible  place  this  latter  slide  on  a  warm  stage 
and  note  the  effect  on  the  white  corpuscles.    In  what  ways 
do  these  cartilage  and  blood  cells  differ  from  the  other  cells 
already  studied,  and  in  what  ways  are  they  similar?    Try 
especially  to  determine  what  represents  the  cell  walls  in 
the  cartilage. 

7.  From  the  data  obtained  in  the  above  studies  write  a 
careful  description  of  the  cell  as  you  understand  it.    Tell 
particularly  what  you  have  found  concerning  the  cell  con- 
tents, and  their  functions. 


PROTOPLASM  OR  LIVING  MATTER. 

IN  the  preceding  study  it  was  found  that  the  cells  were 
of  various  sizes,  shapes,  and  uses.  In  some  were  found 
such  storage  stuffs  as  starch,  fats,  and  mineral  substances, 
in  others,  and  indeed  most,  might  have  been  noted  a  more 
or  less  homogeneous  or  granular  substance  which  has  come 
to  be  known  as  protoplasm,  a  substance  which  Professor 
Huxley  aptly  called  "the  physical  basis  of  life,"  since  life  is 
only  known  to  us  in  association  with  this  physical  material. 
While  a  great  deal  of  investigation  has  been  devoted  to  the 
study  of  protoplasm,  its  chemical  nature  and  its  physical 
structure,  and  while  much  has  been  learned  along  these  lines, 
still  that  which  is  as  yet  unknown  is  much  greater.  An 
elementary  course  wrould  not  be  the  place  to  undertake  a 
study  of  these  properties  of  protoplasm,  yet  it  is  not  beyond 
the  scope  of  even  such  a  course  to  endeavor  to  observe  some 
of  its  more  obvious  characteristics,  and  some  of  the  things 
which  it  does.  It  will  be  interesting  to  study  something  of 
its  actual  activities,  its  movements,  its  behavior  under 
varying  conditions  of  cold  or  warmth,  and  to  note  perhaps 
certain  aspects  of  its  structure.  Since  such  study  can  only 
be  made  with  the  high  power  of  the  microscope  it  will  be 
necessary  to  select  living  things  whose  structure  is  such  as 
to  render  them  favorable  for  observation,  i.  e.,  those  which 
are  sufficiently  transparent  to  enable  one  to  see  through 
them  and  note  all  that  takes  place  within.  Certain  plant 
cells  are  especially  favorable  subjects,  as  are  also  some  of 
the  transparent  animal  organisms,  like  the  common  amoeba. 


48  GENERAL  BIOLOGY 

The  following  types,   among  others   also   available,   afford 
good  material  for  such  study. 

I.  Protoplasmic  Movement. 

1.  Mount  some  of  the  healthy,  younger  leaves  of  Elodea 
in  water  and  with  the  high  power  examine  their  structure. 
In  the  cells  look  for  rather  large  green  bodies,  the  chlorophyll 
bodies.     What  is  their  form  and  how  are  they  arranged  in 
the  cells?    These  bodies  float  in  a  liquid,  the  protoplasm, 
which  is  so  transparent  it  is  exceedingly  difficult  to  see. 

Having  noticed  these  features  of  structure  look  closely 
for  any  signs  of  movement  in  the  cell  contents.  The  move- 
ment is  not  rapid  nor  it  is  continuous,  but  you  should  observe 
it  in  some  of  the  cells  of  the  young  leaves.  Make  a  draw- 
ing of  several  cells,  showing  the  chlorophyll  bodies,  and  by 
arrows  indicate  the  direction  of  movement  of  the  -proto- 
plasm. 

2.  Mount  a  cluster  of  leaves  from  the  tip  of  the  stem  of 
the  stonewort,  Chara  or  Nitella.    The  younger,  more  trans- 
parent cells  in  this  cluster  should  show  the  circulation  of  the 
protoplasm  very    clearly.     It  will    be  necessary  to  focus 
through  the  outer  layer  of  the  protoplasm  wyhich  contains 
the  chlorophyll  bodies,  the  latter  being  stationary  in  this 
form.     Note  the  direction  in  which  the  protoplasm  moves, 
and  whether  all  the  cell  contents  are  involved.    Make  a 
drawing  of  the  cell  as  seen  with  the  high  power,  and  indicate 
by  arrows  in  what  direction  the  protoplasm  is  moving.    It 
may  be  possible  to  see  the  nucleus  wrhich  is  carried  along  by 
the  currents. 

3.  In  the  cultivated  spiderwort  (Tradescantia)  the  stream- 
ing of  protoplasm  is  beautifully  shown.     If  the  flower  of 
this  plant  is  available  take  some  of  the  hairs  which  are 


PROTOPLASM  OR  LIVING  MATTER  49 

present  around  the  stamens,  mount  in  water  and  with  the 
high  power  observe  the  protoplasmic  movements.  Record 
your  observations  in  a  drawing. 

4.  If  amoeba  is  at  hand  observations  should  be  made  on 
the  streaming  or  flowing  movements  of  the  protoplasm. 

II.  Cib'ary  Movement. 

In  certain  cells,  particularly  of  animals,  the  protoplasm 
is  extended  beyond  the  free  ends  of  the  cells  into  very  del- 
icate vibratile  filaments  called  cilia.  Mount  a  small  frag- 
ment of  the  gill  of  a  clam,  or  the  cells  scraped  from  the  roof 
of  the  frog's  mouth,  and  look  for  these  moving  cilia.  Possibly 
the  only  sign  will  be  in  the  currents  of  water  caused  by  the 
movement  of  the  cilia,  the  latter  moving  so  rapidly  they 
can  scarcely  be  seen.  In  a  place  where  the  movement  is 
not  so  rapid  observe  the  direction  in  which  the  cilia  move 
and  whether  they  change  the  direction  of  movement.  Make 
a  drawing. 


THE  CELL. 

CYTOLOGY. 

THE  unfertilized  egg  of  the  starfish  is  a  good  example  of 
a  typical  cell  or  egg.  Other  eggs  as  those  of  Cerebratulus, 
the  large  jellyfish  Aurelia,  or  tissue  cells,  if  large,  may  serve 
equally  well. 

1.  Form.— Are  the  cells  alike  in  shape  and  size?    The 
shape  of  a  'cell,  if  unconfined,  is  usually  spherical,  but  in 
tissues  this  form  is  modified  by  the  pressure  of  adjacent 
cells,  or  as  a  result  of  adaptations  for  some  particular  function. 

2.  Structure.— The  essential  elements   of  every  cell   are 
cell  protoplasm  or  cytoplasm,  and  nucleus.     Is  there  a  mem- 
brane about  the  cell?    Note  the  general  appearance  of  the 
cytoplasm.    Is   it    granular,    fibrillar,    or    alveolar?    Is   the 
cytoplasm  alike  in  all  parts?    In  some  eggs   spheres  or 
granules  of  yolk  are  scattered  through  the  cytoplasm.    In 
what  portion  of  the  cell  is  the  nucleus  located?     Is  this 
position  constant?     Is  there  a  membrane  about  the  nucleus? 
What  is  the  character  of  the  contents  of  the  nucleus?     If 
the  cell  is  stained  note  the  granules,  or  flakes,  within  the 
nucleus  which  stain  more  densely.    These  are  spoken  of  as 
the  chromatin,  the  faintly  stained,  or  unstained,  material  is 
achromatin.     Is  the  chromatin  arranged  in  any  definite  way 
as  though  on  a  framework?     Within  the  nucleus  is  often 
a  rather  large,  deeply,  staining  spot,  the  nucleolus.     Is  it 
in  any  constant  place  in  the  nucleus? 

3.  Cell  Division.— This  fundamental  feature  of  living  things 
presents  two  rather  distinct  and  definite  aspects,  namely, 


THE  CELL  51 

mitotic,  or  indirect  division,  and  amitotic,  or  direct.  The 
latter,  while  apparently  simpler,  involving  the  direct  di- 
vision of  nucleus  and  cytoplasm  by  a  simple  pinching  into 
two  parts,  is  yet  less  common  than  the  former,  and  no 
attempt  will  be  made  to  study  the  process  in  this  connection. 

Mitosis.— In  sections  of  the  root  tip  of  the  onion,  or  of 
the  testis  of  the  grasshopper,  study  the  cells  which  are  in 
the  process  of  division.  Find  a  stage  in  which  the  chromatin 
of  the  nucleus  is  forming  a  long  tangled  thread,  or  else  a 
series  of  densely  staining  bodies.  These  bodies  produced 
from  the  chromatin  of  the  nucleus  are  called  chromosomes. 
Find  a  cell  in  w^hich  the  nuclear  membrane  is  disappearing. 
What  is  the  position  of  the  chromosomes?  Do  you  find 
a  spindle  made  up  of  delicate  fibers  to  which  the  chromo- 
somes are  attached?  In  the  cells  of  some  organisms  there 
is  a  tiny  spot,  the  centrosome,  at  the  end  of  the  spindle  and 
from  this  centrosome  starlike  rays,  the  aster,  radiate  into 
the  cytoplasm. 

Next  examine  a  stage  where  the  chromosomes  are  grouped 
into  a  mass,  or  plate,  at  the  center  of  the  spindle.  At  about 
this  stage  each  chromosome  splits  into  two  parts,  and  the 
halves  separate  and  are  drawn  toward  the  poles  of  the  spindle. 
In  this  position  the  chromosomes  lose  their  distinctness, 
form  a  new  nucleus  with  a  membrane,  the  body  of  the  cell 
divides  into  two  parts  and  we  have  the  division  of  the  cell 
completed. 

The  stage  of  the  formation  of  the  chromosomes  and  their 
arrangement  in  the  spindle  is  called  the  prophase  of  divi- 
sion; the  splitting  of  the  chromosomes  makes  up  the  meta- 
phase;  the  separation  and  the  pulling  apart  of  the  chromo- 
somes comprises  the  anaphase ;  the  formation  of  a  new  nucleus 
and  the  division  of  the  cell  body  is  the  end  or  telophase. 

Make  a  drawing  of  a  cell  in  each  phase  of  division. 


52  GENERAL  BIOLOGY 

It  should  be  clearly  understood  that  the  nuclear  changes 
described  above  constitute  an  uninterrupted  process.  The 
separation  of  the  process  into  distinct -phases  or  stages  is 
made  for  convenience  in  description  and  analysis.  The  prep- 
arations on  the  slides  which  show  the  distinct  phases,  there- 
fore, represent  cells  which  were  killed  in  the  midst  of  the 
process,  and  which  were  permanently  fixed  in  this  condition. 

4.  Cleavage  and  Development.— In  order  that  an  egg  may 
develop  and  grow  into  a  new  organism  several  preparatory 
processes  are  essential.  First  a  ripening  or  maturation 
process  is  necessary  for  both  the  female  reproductive  cells 
(ova  or  eggs)  and  the  male  reproductive  cells  (spermatozoa). 
After  maturation  fertilization  must  occur,  and  this  consists 
in  the  union  of  an  ovum  and  a  spermatozoon.  The  fertilized 
egg  is  now  capable  of  further  development  which  is  initiated 
by  a  division  into  cells,  a  process  called  cleavage  or  segmen- 
tation. 

In  dividing  starfish  eggs  look  for  stages  of  2-,  4-,  8-  cells. 
Are  these  cells  enclosed  within  a  membrane?  Are  they  of 
equal  size?  Each  cell  continues  to  divide  until  a  large 
number  are  present,  and  these  are  arranged  in  the  form  of 
a  hollow  sphere,  the  blastula.  Are  all  the  cells  of  the  blastula 
of  the  same  size?  Look  for  other  stages  in  which  one  side 
of  the  blastula  is  flattened  or  pushed  into  the  hollow  of  the 
sphere.  Such  a  stage  is  spoken  of  as  the  gastmla  and  is 
really  a  double-walled  sac  or  embryo,  the  outer  wall  mak- 
ing up  the  ectoderm  and  the  inner  the  entoderm.  Later  a 
middle  layer  or  mesoderm,  is  formed  between  the  ectoderm 
and  the  entoderm.  These  three  layers  are  the  germ  layers 
of  the  embryo  from  which  are  differentiated  the  organs  of 
the  developing  organism. 

Study  and  draw  several  stages  of  cleavage,  of  the  blastula 
and  gastrula  formation. 


THE  CELL  53 

In  the  development  of  any  animal  it  may  be  stated  that, 
from  the  outer  germ  layer,  or  ectoderm  are  formed  the  cover- 
ing of  the  body  with  its  protective  structures  such  as  scales, 
feathers  and  the  like,  the  nervous  system  and  the  sense 
organs.  The  entoderm  or  inner  germ  layer  gives  rise  to  the 
lining  of  the  digestive  tube,  the  gland  cells  of  liver,  pan- 
creas and  stomach,  the  lining  of  lungs  and  trachea.  From 
the  mesoderm  are  derived  the  muscle,  bone,  connective  tissue, 
blood,  heart  and  bloodvessels,  the  kidney,  reproductive 
organs  and  their  ducts. 


AMOEBA 

THE  PROTEUS  ANIMALCULE. 

AMCEB.E  are  among  the  simplest  of  living  things,  they 
look  like  tiny  drops  of  clear  jelly  usually  somewhat 
granular  within.  The  amoeba  will  be  almost  constantly 
moving  and  changing  its  shape,  whence  it  gets  the  name  of 
"proteus"  animalcule.  This  habit  of  changing  the  shape 
is  one  of  the  surest  methods  of  identifying  the  animal. 

Mount  on  a  slide  some  of  the  sediment  from  the  dish  sup- 
posed to  contain  amoebae,  cover  with  a  cover  glass  and  search 
for  an  amoeba  with  the  low  power.  If  one  is  not  found 
wait  several  minutes  and  examine  again;  in  this  time  the 
amoeba  may  have  crawled  out  from  the  sediment.  When 
an  amoeba  is  found  examine  with  the  high  power.  Be 
careful  not  to  move  the  slide  enough  to  lose  the  animal. 

I.  Morphology. 

1.  Form.— Note  the  changing  shape,   and  the  root-like 
prolongations  of  the  body  called  pseudopodia.     Are  these 
pseudopodia  alike?    How  many  are  there?    Is  the  number 
constant?     Can  you  discover  their  function?    Make  a  series 
of  10  outline  drawings  (each  about  an  inch  long)  at  intervals 
of  two  or  three  minutes.    By  means  of  arrows  indicate  the 
direction  of  movement  of  the  protoplasm. 

2.  Structure.— The  protoplasm  which  makes  up  the  sub- 
stance of  the  animal  is  composed  of  an  inner  part  called  the 
entoplasm,    and   an   outer   ectoplasm.     How   are   they   dis- 
tinguished?   May   these   distinctions   be   traced   into   the 


AMCEBA  55 

pseudopodia?  Is  the  boundary  between  the  two  parts  a 
sharp  one?  Which  layer  is  the  more  fluid?  Is  there  a 
definite  membrane  about  the  animal  ? 

Within  the  entoplasm  may  be  seen  food  vacuoles  which 
are  usually  rather  small  and  spherical,  though  they  may  be 
quite  large  and  of  irregular  shape,  depending  upon  the  kind 
of  food  which  has  been  eaten.  Do  you  find  what  might  be 
considered  as  lifeless  material  such  as  crystals,  oil  drops,  and 
the  like?  In  the  entoplasm  may  also  be  found  the  contractile 
vacuole,  a  transparent,  spherical  body  which  disappears  and 
reappears  at  intervals.  Its  function  appears  to  be  excretory. 

Sometimes  the  nucleus  can  be  seen.  This  is  a  circular  or 
oval,  denser  body,  usually  granular  in  appearance.  Does 
it  occupy  a  definite  and  constant  position  in  the  amoeba? 
If  it  cannot  be  seen  in  the  living  animal  examine  one  of  the 
stained  and  mounted  specimens. 

Make  a  drawing  about  two  inches  in  diameter,  fill  in,  and 
label  all  the  details  mentioned  above. 

II.  Physiology. 

1.  Movements.— Is  motion  continuous?     Regular?     How 
is   it  produced?     Is   there   any   definiteness   of  direction? 
Watch  the  formation  of  a  pseudopodium  and  describe  what 
part  the  ectoplasm  and  entoplasm  play  in  the  process.     Are 
the  currents  in  the  entoplasm  at  all  constant?    Where  are 
they  the  swiftest,  where  slowest?    Trace  on  paper  the  path 
that  an  amoeba  has  taken  in  the  time  under  observation. 

2.  Nutrition.— If   opportunity    oft'ers   determine   how    an 
amoeba  eats,  and  how  it  gets  rid  of  waste  matter.      From 
an  examination  of  the  food  vacuoles  determine,  if  possible, 
what  the  animal  eats.    Look  especially  for  diatoms  and 
desmids  and  for  small  protozoa.     Is  there  a  definite  course 


56  GENERAL  BIOLOGY 

of  food  particles  in  the  body?    Where  is  the  food  digested? 
How  is  it  distributed  ? 

3.  Sensation.— Does  the  amoeba  ever  appear  to  feel  an 
object  against  which  it  presses?    Does  it  avoid  obstacles? 
Tap  the  cover  with  a  needle,  are  there  indications  that  the 
animal  has  the  sense  of  touch?    If  the  slide  is  placed  upon 
a  warm  stage  it  may  be  possible  to  determine  whether  the 
animal  responds  to  temperature.    If  heated  to  40°  C.  the 
amoeba  will  be  killed. 

4.  Reproduction.— Occasionally   one   meets   some   of   the 
stages  that  the  animal  undergoes  in  its  life  history,  such  as 
encysted    specimens    and    specimens    undergoing    division. 
If  any  of  these  stages  are  found  examine  them  with  care 
and  make  drawings  of  them. 

Various  kinds,  or  species,  of  amoebae  may  be  found  which 
may  differ  in  number,  shape  and  position  of  the  pseudopodia; 
in  size  and  abundance  of  granules  in  the  entoplasm;  and 
in  the  presence  of  a  shell  about  the  animal. 


PARAMECIUM. 

THE  SLIPPER  ANIMALCULE. 

PARAMECIUM  is  found  in  water  containing  decaying 
organic  matter,  i.  e.,  in  infusions  of  organic  matter  hence 
the  name  infusoria,  the  class  to  which  the  animal  belongs. 
In  nature  Paramecium  will  be  found  in  almost  any  ditch 
or  pond  which  contains  much  organic  matter.  In  a  jar 
containing  an  infusion  of  hay  the  paramecia  are  usually 
found  near  the  surface  and  often  in  a  ring  around  the  edge 
of  the  dish.  Mount  a  drop  of  water  from  this  region  of  the 
dish,  first  placing  a  thin  layer  of  cotton  on  the  slide  to  trap 
the  animals,  or  a  solution  of  gum  to  lessen  the  activity. 
Examine  with  the  low  power. 

I.  Morphology. 

1.  Form.— Are  there  individual  differences  in  size?    Can 
the  animals  be  seen  with  the  naked  eye?    In  outline  the 
animal  is  elliptical  or  oval,    often  rather    slipper-shaped, 
whence  comes  the  name  "slipper  animalcule."     Is  the  shape 
constant  under  all  conditions?    Watch  one  while  it  is  pass- 
ing through  a  narrow  space.     Is  the  body  rigid  or  flexible? 
Are  there  definite  anterior  and  posterior  ends?    If  so,  how 
are  they  distinguished? 

With  a  piece  of  clay  make  a  model  of  the  paramecium. 
Be  careful  to  get  the  right  proportions  and  shape. 

2.  Structure.— Along  one  side  of  the  animal  is  a  groove 
which  leads  to  a  mouth  opening.    The  most  satisfactory 


58  GENERAL  &IOLOGY 

way  to  observe  this  groove,  the  buccal  groove,  is  to  watch 
the  animal  as  it  rotates  on  the  long  axis  (use  the  low  power). 
In  the  clay  model  already  constructed  indicate  the  position 
and  shape  of  this  groove. 

Examine  with  the  high  power.  If  the  movements  are 
not  sufficiently  restricted  to  allow  the  examination  of  speci- 
mens with  the  high  power,  place  them  in  a  rather  thick 
gelatin  solution,  which  will  retard  their  movements.  Or  one 
may  try  the  following  scheme:  on  a  slide  without  cotton  place 
a  drop  of  the  water  containing  the  animals  and  cover  with 
the  cover  glass.  With  a  piece  of  filter  paper  applied  to  the 
edge  of  the  cover  glass  slowly  draw  some  of  the  water  from 
under  the  cover.  Continue  until  the  cover  begins  to  touch 
the  animals  and  to  flatten  them  slightly.  At  this  point  it 
will  be  found  that  the  paramecia  do  not  have  room  to  move 
about  and,  being  flattened  somewhat,  the  internal  structure 
is  more  evident.  The  success  depends  upon  the  remova 
of  just  the  right  amount  of  water.  Remember  the  shape 
of  the  animals  under  these  conditions  is  considerably  dis- 
torted, and  some  of  the  structures  are  not  normal. 

Can  you  distinguish  an  ectoplasm  and  an  entoplasm?  In 
what  ways  are  these  like,  or  unlike,  the  same  parts  of  amoeba? 
In  a  quiet  specimen  observe  the  ectoplasm  carefully  and 
look  for  a  delicate  outer  layer,  the  cuticle,  which  serves  as 
a  cell  wall.  Fine,  hair-like,  protoplasmic  processes,  the 
cilia,  project  from  the  surface  of  the  body.  Are  these  cilia 
present  on  all  parts  of  the  body?  Are  they  of  uniform 
length?  In  the  deeper  part  of  the  ectoplasm  are  minute 
oval  sacs  called  trichocysts,  arranged  perpendicular  to  the 
surface.  Very  often  they  look  like  short  stiff  rods  rather  than 
sacs.  The  contents  of  these  sacs  may  be  forced  out  beyond 
the  cilia,  or  even  entirely  out  of  the  body,  and  appear  as 
rather  thick  threads  in  the  water.  The  tangle  of  threads 


PARAMECIUM  59 

so  produced  seems  to  serve  as  something  of  a  protection  to 
Paramecium. 

Within  the  entoplasm  are  food  vacuoles,  masses  of  food 
forming  little  spheres  or  globules  and  surrounded  by  a  little 
liquid.  Are  these  of  the  same  size?  Where  in  the  body 
are  they  most  abundant?  Do  they  resemble  the  food 
vacuoles  of  amreba?  Do  you  find  contractile  vacuoles? 
How  many?  Where  situated?  Is  the  contraction  or  the 
expansion  more  rapid?  Just  after  the  disappearance  of 
the  vacuole  look  closely  for  radiating  canals  in  the  same 
region.  If  more  than  one  vacuole  is  present  observe  whether 
they  contract  and  expand  together.  What  is  the  nature 
of  the  contents  of  the  contractile  vacuoles?  What  function 
might  they  serve? 

The  nucleus  can  rarely  be  seen  in  the  living  animal.  In 
order  to  render  it.  visible  place  a  drop  of  methyl  green  near 
the  cover  glass  and  draw  it  underneath  by  the -use  of  filter 
paper.  When  the  excess  of  stain  is  replaced  by  clean  water, 
the  nucleus  should  be  visible  as  a  green  spot.  In  what  part 
of  the  body  is  the  nucleus?  This  nucleus  is  called  the 
macronucleus  and  is  rather  large;  by  its  side  is  a  smaller 
nucleus,  the  micronucleus,  which  is  difficult  to  demonstrate 
except  by  special  means  of  preparation. 

A  drawing  about  four  inches  long  should  be  made  and  in 
it  should  be  represented  all  the  details  of  structure  mentioned 
above.  Also  make  a  drawing  of  an  ideal  cross  section  of 
the  animal  through  the  middle  region  of  the  body. 

II.  Physiology. 

1.  Movements.— In  what  directions  may  the  animal  move? 
What  are  the  means  of  locomotion?  Run  some  powdered 
carmine  under  the  cover  glass  and  observe  the  currents 


60  GENERAL  BIOLOGY 

produced  by  the  action  of  the  cilia.  What  is  the  general 
direction  over  the  surface  of  the  body?  In  the  mouth 
groove? 

2.  Defense.— Run  some  dilute  picric  acid  under  the  cover 
and  observe  the  trichocysts  which  are  thrown  out.    In  a 
drawing  show  the  trichocysts  and  the  cilia. 

3.  Nutrition.— (a)   Ingestion    of    food.— Place    some   para- 
mecia  on  a  slide  with  a  small  amount  of  powdered  carmine 
in  water  and  watch  the  formation  of  a  food  ball  in  the  gullet, 
and  the  way  in  which  it  is  taken  into  the  body.    When  it 
gets  into  the  body  it  becomes  a  food  vacuole. 

(6)  Nature  of  the  Food.— Study  the  contents  of  the  food 
vacuoles  found  naturally  in  the  body  and  determine,  if 
possible,  what  the  Paramecium  feeds  upon,  especially 
whether  it  is  plant  or  animal  food. 

(c)  Digestion.— Observe  the  changes  in  form,  size  and 
amount  which  take  place  in  the  food  as  it  passes  through 
the  body.  Are  there  changes  in  the  food  vacuole?  What 
do  they  mean? 

4.  Circulation  of  the  Protoplasm. —Watch  the  food  vacuoles, 
especially  after  having  added  the  carmine,  and  see  whether 
they  change  their  position  in  the  body.    If  there  is  any 
movement  make  an  outline  drawing  and  show  by  arrows 
the  course  of  the  circulation. 

5.  Irritability.— What  reasons  are  there  for  believing  that 
Paramecium  is  sensitive  to  external  influences?    Do  they 
avoid  objects?    Do  they  collide  with  each  other  in  motion? 
Do  they  tend  to  collect  in  masses?    Where?    Why?    Are 
they  as  active  at  the  end  of  the  hour  as  at  the  beginning? 
Why  ?    Is  the  animal  sensitive  to  touch  or  pressure  ? 

6.  Reproduction.  — (a)  .Fission.— This  is  the  usual  method  of 
reproduction  and  consists  in  the  division  of  the  animal  into 
two  parts.    At  what  part  of  the  body  and  in  what  direction 


PARAMECIUM  61 

is  the  line  of  division?  Can  one  speak  of  "parent"  and 
"offspring"?  Stain  the  dividing  animals  with  methyl  green 
and  note  what  changes  are  taking  place  in  the  nucleus. 

(6)  Conjugation.— This  is  of  less  common  occurrence 
and  depends  in  part  upon  the  physiological  condition  of  the 
animals.  Look  for  pairs  of  individuals  which  are  joined 
together  by  the  buccal  groove.  This  contact  of  the  animals 
is  only  temporary  for  they  later  separate;  in  the  meantime, 
however,  portions  of  the  nuclei  have  been  exchanged.  If 
slides  with  stained  specimens  showing  conjugation  are  at 
hand  examine  them  for  the  nuclear  changes  involved.  Is 
there  any  distinction  of  sex  in  these  conjugating  individuals? 


VORTICELLA. 

THE  BELL  ANIMALCULE. 

MOUNT  some  of  the  scum  from  the  top  of  the  water  in 
a  jar  containing  Vorticella,  and  look  for  tiny  bell  shaped 
organisms  borne  on  a  stalk.  They  are  much  smaller  than 
Paramecium  and  are  usually  in  groups  or  colonies.  Be 
sure  that  there  is  plenty  of  water  and  that  the  cover  does 
not  press  on  the  animals  and  distort  them.  It  will  not  be 
necessary  to  have  a  layer  of  cotton  on  the  slide,  since  the 
animals  are  fastened  to  a  stalk  and  will  not  swim  away. 

I.  Morphology. 

1.  The  Stalk.— What  is  its  shape?    Its  length  as  com- 
pared with  its  width?    Its  shape  when  it  is  contracted  and 
when  expanded?    In  the  stalk  there  is  present  cuticle  and 
ectoplasm  but  no  entoplasm.    The  central  axis  (ectoplasm) 
is  usually  easily  seen.    Does  it  run  through  the  exact  center 
of  the  stalk?    With  your  highest  power  study  the  structure 
of  this  stalk  and  make  a  drawing  of  it,  very  much  magnified, 
showing  how  it  is  constructed  and  how  it  connects  with  the 
body  of  the  animal.    Can  you  give  any  explanation  for  the 
coiling  of  the  stalk  when  it  contracts? 

2.  The  Body.— What  is  the  shape  when  seen  from  above? 
from  the  side?    When  the  animal  is  contracted?    when 
it  is  fully  expanded?    In  a  fully  expanded  individual  note 
the  peristome  or  rounded  edge  of  the  bell.    Does  it  extend 
completely  around   the  bell?    The  top  of  the  animal   is 


VORTICELLA  63 

raised  in  the  form  of  a  dome  or  plate,  forming  the  disk. 
Between  the  peristome  and  the  disk  is  a  gutter-like  depres- 
sion leading  into  a  deep  pit,  the  vestibule.  Is  there  anything 
in  Paramecium  which  corresponds  to  this  vestibule?  From 
the  vestibule  the  esophagus  extends  downward.  Trace  its 
direction  and  determine  its  shape.  In  Vorticella  where 
are  the  cilia  located  and  how  are  they  arranged? 

In  the  body  look  for  a  transparent  covering,  the  cuticle. 
Is  there  ectoplasm  and  entoplasm  as  in  Amoeba  and  Para- 
mecium? Is  the  differentiation  of  these  layers  as  marked 
as  in  the  other  protozoa  studied?  Are  food  vacuoles  present? 
Are  there  contractile  vacuoles ?  How  many?  Where  located? 
The  nucleus  is  an  elongated  horse  shoe  or  "C"  shaped  mass 
in  the  entoplasm.  It  may  be  more  easily  found  if  the  animals 
are  stained  with  methyl  green.  A  micronucleus  is  present, 
but  is  so  small  as  to  be  found  only  with  great  difficulty. 

II.  Physiology. 

1.  General  Movements.— Observe  the  manner  in  which  the 
stalk  contracts.  What  changes  take  place  in  the  body 
during  this  contraction?  May  the  body  contract  without 
a  contraction  of  the  stalk?  Note  the  rapidity  of  the  move- 
ments in  the  contraction  and  in  the  expansion.  How  does 
the  animal  assume  the  expanded  condition?  Which  is  the 
part  to  first  assume  the  expanded  condition?  Note  that 
in  some  cases  there  is  no  stalk  attached  to  the  animals.  How 
do  they  behave  when  this  is  the  case?  Vorticella  may 
separate  from  its  stalk  and  become  free-swimming  for  a  time. 
During  this  period  a  second  row  of  cilia  develops  about  the 
base  of  the  bell,  to  aid  in  locomotion.  (In  some  cases  this 
separation  from  the  stalk  is  not  normal,  but  is  due  to  pressure 
from  the  cover  glass  or  to  some  other  unusual  condition;  in 


64  GENERAL  BIOLOGY 

such  instances  the  cilia  are  like  those  in  the  normal  stalked 
form.) 

2.  Ciliary    Movements. —Add   powdered    carmine   to    the 
water  and  observe  the  directions  of  the  currents  produced 
and  also  the  method  of  feeding.    Watch  the  formation  of 
a  food  vacuole.    If  there  is  a  movement  of  these  in  the  body 
indicate  by  arrows  in  a  drawing  the  course  taken. 

3.  Irritability.— Notice  what  happens  when  the  slide  or 
cover  is  tapped,  and  when  the  animal  is  touched  by  some- 
thing.   Is  Vorticella  more  or  less  sensitive  than  Paramecium  ? 
Does  it  always  contract  when  it  touches  something?    Ex- 
plain. 

4.  Reproduction.  —  (a)  Fission.    Look  for  individuals  un- 
dergoing fission.    Where  does  the  division  begin?    In  what 
direction  does  the  division  take  place?    After  the  division 
is  completed  one  of  the  two  new  animals  separates  from  the 
stalk,  swims  away  and  later  settles  down,  forming  a  new 
stalk. 

(6)  Conjugation.— Individuals  may  rarely  be  found  under- 
going conjugation.  In  Vorticella  this  involves  the  per- 
manent union  and  fusion  of  a  small  individual  with  one  of 
the  normal  stalked  forms. 

Questions  on  the  Protozoa  in  General. 

Tell  something  of  the  shape  of  protozoa,  of  their  size.  Is 
the  body  symmetrical?  Is  the  shape  constant?  Is  there 
any  distinction  of  the  animals  into  regions?  What  sorts 
of  motions  have  the  animals?  How  are  these  movements 
produced?  Do  all  the  protozoa  examined  have  the  same 
motor  apparatus?  Does  the  body  contain  blood  and  is  a 
heart  present?  Is  there  anything  corresponding  to  stomach, 
lungs,  or  gills?  Do  the  animals  eat,  digest  food,  breathe, 


VORTICELLA  65 

see,  feel?  Do  they  have  nerves  or  brain?  If  the  organs 
needed  for  performing  these  functions  in  other  animals  are 
absent  in  the  protozoa,  how  can  you  account  for  the  fact 
that  they  do  perform  these  functions? 

Is  the  protoplasm  protected  in  any  way?  What  means 
of  defense  have  they?  How  can  one  account  for  their  wide 
distribution  and  abundance? 

In  what  ways  do  these  single  celled  animals  differ  from 
the  single  cells  of  plants  and  of  higher  animals?  In  what 
ways  do  they  resemble  each  other?  Could  single  cells  from 
the  many-celled  animals  exist  alone  as  do  the  Protozoa? 

Write  a  brief  paper  answering  the  questions  above  and 
discuss  the  points  suggested. 


PLEUROCOCCUS. 

PLEUROCOCCUS  is  a  unicellular  plant,  growing  on  damp 
stones  or  ground,  and  is  very  common  upon  the  trunks  of 
trees. 

I.  Morphology. 

1.  General   Structure.— Note  the   appearance  of  Pleuro- 
coccus  in  its  natural  growth  on  a  piece  of  bark  or  damp  wood. 
Is  it  evenly  distributed  over  the  surface?     Compare  several 
specimens  of  bark  on  this  point.    What  is  the  color?    Does 
it  vary  in  different  specimens?     Compare  pieces  of  dry  bark, 
and  those  which  have  been  in  a  moist  place  for  several  days. 

2.  Minute  Structure.— Scrape  bits  of  the  plant  from  the 
bark  and  mount  on  a  slide  with  water.      Examine  first 
with  the  low  power,  arid  then  with  the  high  power  of  the 
microscope.    Note  the  form  of  the  cells,  and  whether  they 
are  single  or  associated  in  definite  groups.     Make  drawings 
of  any  different  appearances  found. 

Is  there  a  cell  wall?  What  is  its  color?  Can  the  proto- 
plasm be  seen?  The  green  color  of  the  plant  is  due  to  the 
presence  of  chlorophyll;  usually  this  is  distributed  through- 
out the  protoplasm,  though  it  may  be  in  several  distinct 
chloroplasts  or  chlorophyll  bodies.  Is  there  any  nucleus 
which  can  be  seen  in  the  living  cells? 

n.  Reproduction. 

Look  for  cells  which  are  in  the  process  of  division  to  form 
groups  of  two,  three,  four  or  more  cells.  This  is  the  ordinary 


PLEUROCOCCUS  67 

mode  of  propagation  by  Pleurococcus.    Is  there  any  regular 
order  in  the  number  of  cells  produced  ? 

In  some  unicellular  plants  similar  to  Pleurococcus  an- 
other sort  of  reproduction  occurs,  viz.,  by  a  division  within 
the  cell  there  are  formed  a  number  of  motile  cells  called 
zoospores.  These  may  be  of  two  sizes,  the  larger  ones  called 
macrozobspores,  and  the  smaller  ones  microzoospores.  Lo- 
comotion of  these  spores  is  by  means  of  flagella.  Can  you 
suggest  any  advantage  in  having  a  zoospore  stage?  A 
conjugation  of  macrozoospores  and  microzoospores  may 


COLONIAL  PROTOZOA. 

AMONG  protozoa  are  to  be  found  various  species  which, 
instead  of  becoming  independent  and  separating  from  their 
fellows  at  once  after  division,  remain  for  some  time,  or  per- 
manently, associated  in  colonies.  The  formation  of  groups 
or  companies  was  noted  in  Vorticella.  Other  vorticella- 
like  animals  (Carchesium,  Epistylis)  may  be  grouped  into 
permanent,  branching,  tree-like  masses.  Gonium,  Pandorina, 
Volvox,  are  well-known  examples  of  free-swimming  colonies. 
Such  forms  are  especially  interesting  for  they  show  the  be- 
ginning of  differentiation  and  complexity  in  a  phylum  com- 
prising the  simplest  organisms.  They  are  further  interesting, 
(a)  in  suggesting  a  possible  origin  of  multicellular  organisms ; 
(6)  in  that  their  animal  or  plant  affinities  are  still  open  to 
question. 

As  a  type  of  these  colonial  forms  Volvox  is  suggested  for 
study.  It  may  often  be  collected  in  the  spring  or  fall  from 
small  lakes  or  ponds  containing  Riccia,  duck-weed  and  other 
plants.  By  stocking  jars  from  the  water  of  ponds  where 
the  organisms  are  found,  and  maintaining  conditions  as 
nearly  normal  as  possible,  they  may  be  kept  in  the  labora- 
tory for  several  weeks. 

I.  Morphology. 

1.  Form  of  Colony. -What  is  the  general  shape?  Color? 
If  living,  note  the  movements  of  the  colony  and  determine 
how  it  is  produced.  Of  how  many  kinds  of  cells  is  the 


COLONIAL  PROTOZOA  69 

colony  composed?  How  do  they  differ  in  size,  position, 
and  shape? 

2.  Structure.— Note  the  size,  shape,  and  large  number  of 
cells  which  make  up  the  body  of  the  organism.  How  are 
the  cells  connected  with  each  other?  Under  high  power 
make  out  the  flagella  of  the  cells.  How  many  has  each  cell? 
With  what  part  of  the  cell  are  they  connected? 

Make  a  careful  drawing  of  a  group  of  cells,  their  structure, 
and  connection  to  other  cells. 

n.  Physiology. 

1.  Reproduction.  —  (a)  Asexual.  Certain  cells,  partheno- 
gonidia,  migrate  from  the  outer  wall  into  the  interior  of  the 
sphere  and  there,  without  fertilization,  give  rise  to  small 
colonies  by  repeated  divisions. 

(6)  Sexual.— Other  cells  which  move  into  the  interior  of 
the  sphere  are  specialized  reproductive  cells.  The  egg 
(macrogamete)  is  large,  the  spermatozoids  (microgametes) 
are  small.  These  two  kinds  of  cells  fuse  or  conjugate  and 
the  fertilized  egg  develops  into  a  new  colony. 

Make  drawings  of  different  stages  of  reproduction,  both 
sexual  and  asexual. 

Would  you  regard  Volvox  as  a  unicellular  colony  or  as  a 
very  simple  multicellular  organism?  Give  reasons  for  your 
conclusion. 


SPIBOGYRA. 

POND  SCUM. 

SPIROGYRA  is  a  filamentous  alga  common  in  ponds, 
ditches,  or  sluggish  streams  during  the  summer  months, 
usually  floating  on  the  surface  or  adhering  lightly  to  some 
support.  It  is  often  called  "pond  scum,"  "frog-spittle," 
"brook-silk."  The  scientific  name  comes  from  the  spiral 
arrangement  of  the  chlorophyll  in  the  cells.  The  alga  may 
be  collected  late  in  the  fall  and  kept  in  aquaria  all  winter, 
usually  in  good  condition. 

I.  Morphology. 

1.  General  Characters.— Note  the  color,  texture,  slippery 
feeling.    Do    different    masses    show    variations    in    these 
respects  ?    To  what  extent  ? 

2.  Microscopic    Characters.— Mount    a    few   filaments    in 
water  and  examine  with  low,  and  with  high  powers. 

(a)  Shape  of  Filament.— Is  it  simple  or  branched?  Is 
it  of  uniform  size?  Are  there  signs  of  roots?  Is  there  a 
root  end  or  a  tip  to  the  filament? 

(6)  Structure.— Is  the  filament  composed  of  cells?  If 
so  are  they  of  uniform  size?  Note  any  variations.  How 
are  the  cells  united?  Is  a  cell  wall  clearly  distinguishable? 
Is  it  of  uniform  thickness  over  all  portions  of  the  cell?  Stain 
the  filament  by  running  a  drop  of  iodine  under  the  cover 
glass  and  note  effects  on  all  parts  of  the  cell.  Are  there 
indications  of  starch? 


SPIROGYRA  71 

Mount  fresh  filaments  and  study  the  chlorophyll  bands, 
or  chloroplasts.  What  is  their  general  form?  How  many 
in  a  cell?  How  many  spirals  of  the  chloroplast  in  a  single 
cell?  Note  the  form  of  the  margin  of  the  band.  What 
relation  has  ;this  to  certain  round  bodies,  the  pyrenoids, 
situated  at  regular  intervals  along  the  bands?  Test  for 
starch  in  the  pyrenoids  and  surrounding  granules. 

(c)  Nucleus.— Examine  the  cells  in  both  fresh  and  stained 
condition  for  the  nucleus.  Does  it  occupy  the  same  position 
in  all  cells  ?  What  is  its  shape  ? 

Make  drawings  to  show  the  points  observed. 

II.  Physiology. 

1.  Plasmolysis.— In  fresh  specimens  look  for  a  very  deli- 
cate film  of  protoplasm  lining  the  cell  wall.     If  it  cannot 
be  found  in  fresh  specimens  try  the  following  experiment  of 
plasmolyzing  the  cell:    Run  a  few  drops  of  a  10  per  cent 
solution  of  salt  or  sugar  under  the  cover  glass,  and  note 
what  happens  to  the  protoplasm.     Is  there  any  change  in 
the  cell  wall?     In  the  chloroplast?     During  the   experiment, 
and  probably  before,  vacuoles  will  have  been  noted  in  the 
cells.     What  effect  had  plasmolysis  upon  these?     Explain. 

2.  Photosynthesis.— Study  the  effects  of  light  on  starch 
making  by  examining  specimens  which  have  been  kept  in 
the  dark  for  twenty-four  hours  and  testing  for  starch.    Com- 
pare with  specimens  which  have  been  freely  exposed  to  light. 
What  conclusions  may  be  drawn? 

3.  Reproduction.— Occasionally    during    the    summer    or 
fall  Spirogyra  may  be  found  in  the  process  of  conjugation. 
This  consists  in  the  union  of  cells  of  two  parallel  filaments 
lying  close  together   by  outgrowths  of  tubular  processes 
from  each  cell,  and  their  final  fusion  with  those  of  the  adjacent 


72  GENERAL  BIOLOGY 

cell.  In  this  way  there  is  a  fusion  of  the  protoplasm  of  the 
two  cells. 

If  filaments  are  found  in  this  condition  note  any  differences 
in  color  and  size  of  the  filaments  and  cells,  as  compared  with 
the  ordinary  condition.  Are  all  the  cells  of  the  filaments 
undergoing  conjugation  in  the  same  stages  of  conjugation? 
Does  the  chloroplast  take  part  in  the  process? 

The  result  of  this  conjugation  is  the  formation  of  a  zygo- 
spore.  What  is  its  shape?  Color?  Size?  Are  zygospores 
found  in  cells  of  both  the  conjugating  filaments?  Is  there 
any  indication  of  sexual  distinction  in  the  two  filaments? 
In  what  condition  are  the  old  cells  after  conjugation  is  com- 
plete? 


SPONGE. 

GRANTIA  SP. 

A  FEW  sponges  are  found  in  fresh  water,  but  most  are 
marine;  the  latter  are  found  in  all  parts  of  the  world  under  a 
great  variety  of  conditions.  Grantia  is  a  solitary  form, 
not  producing  colonies  as  do  many  others,  though  buds  at 
its  base  may  temporarily  make  a  small  colony.  It  is  per- 
manently attached  to  rocks,  piles  and  sea-weed  below  low- 
water  mark. 

I.  External  Anatomy. 

Place  a  specimen  in  a  watch  glass  in  water  or  alcohol. 
Observe  the  form  of  the  animal,  and  its  mode  of  attach- 
ment. At  the  free  end  note  the  opening,  the  osculum, 
partly  covered  and  protected  by  a  cluster  of  spicules.  This 
opening  is  not  a  mouth,  but  an  excurrent  opening  for  the 
discharge  of  water  from  the  animal.  In  the  sides  of  the 
animal  are  many  minute  openings,  the  incurrent  pores  or 
ostia.  Are  these  covered  or  protected  by  spicules  like  the 
osculum? 

Make  a  drawing  of  a  specimen. 

II.  Internal  Anatomy. 

With  a  razor  cut  a  dry  specimen  longitudinally  and  ex- 
amine the  section  with  a  lens.  Observe  the  central  cavity 
and  the  small  pores,  the  apopyles,  which  pierce  its  wall.  In 
the  walls  find  a  series  of  canals  arranged  in  radial  fashion. 


74  GENERAL  BIOLOGY 

These  are  of  two  sorts,  incurrent  canals  open  to  the  outside, 
and  radial  canals  or  flagellated  chambers  which  open  into 
the  central  cavity. 
Draw  the  sectioned  specimen. 

III.  Microscopic  Sections. 

Study  stained  sections  made  transversely  through  a 
decalcified  specimen.  Make  a  careful  study  of  the  arrange- 
ments of  the  parallel  tubes  in  the  walls,  and  their  relation 
to  the  central  cavity.  Are  the  tubes  open  at  both  ends? 
Is  it  possible  to  distinguish  the  incurrent  and  the  radial 
canals?  What  structural  features  make  this  distinction 
possible?  Are  there  any  openings,  the  prosopyles,  between 
the  incurrent  and  radial  canals? 

With  the  highest  power  examine  the  cells.  The  central 
cavity  is  lined  by  flat  or  pavement  epithelium;  the  radial 
canals  are  lined  by  peculiar  cells,  the  gastral  epithelium,  or 
choanocytes,  which  are  elongated  cells  bearing  flagella;  the 
incurrent  canals  and  the  outer  surface  of  the  body  are  cov- 
ered with  flattened  cells,  the  dermal  epithelium.  Scattered 
through  the  sections  may  be  found  germ  cells,  sperms  or 
eggs  or  segmenting  eggs.  Observe  especially  their  location 
with  regard  to  the  cellular  layers. 

Make  a  careful  drawing  of  a  portion  of  a  transverse 
section. 

IV.  Skeleton. 

If  a  specimen  is  boiled  in  caustic' potash  the  fleshy  matter 
will  be  destroyed,  leaving  only  the  skeleton.  The  latter  is 
made  up  of  a  series  of  spicules  embedded  in  the  flesh.  Mount 
some  of  these  loose  spicules  in  water  and  examine  with 
the  microscope.  Draw  the  different  kinds  found. 


HYDRA. 

HYDRA  is  found  in  ponds  and  lakes  which  contain  pond 
weeds  such  as,  Elodea,  Sagittaria,  water-lilies,  duck  weed, 
and  the  like,  usually  being  attached  to  these  plants.  Speci- 
mens secured  .  from  such  localities  and  placed  in  aquaria 
with  aquatic  plants  will  live  indefinitely,  if  supplied  with 
food  in  the  form  of  small  Crustacea  or  "water-fleas." 

From  the  aquaria  in  the  laboratory  remove  hydra  with 
a  clean  pipette  and  place  in  a  watch  glass  with  water  from 
the  aquarium.  Place  this  dish  on  the  stage  of  the  dissecting 
microscope  and  examine  the  specimens. 

I.  Morphology. 

1.  Form.— Describe  the  shape  and  color  of  the  animal. 
Is  the  body  differentiated  into  regions  as  head  and  base? 
Is  it  attached  or  free?  Do  the  length  and  breadth  remain 
constant?  At  the  free  end  of  the  body  is  a  row  of  tentacles, 
how  many  are  there?  Is  the  number  the  same  in  all  speci- 
mens? Compare  notes  with  other  students  to  determine 
this.  If  both  the  green  and  the  brown  hydra  are  available 
compare  them  in  number  of  tentacles.  Are  the  tentacles 
smooth  and  even  in  contour?  Compare  the  length  and  the 
shape  of  the  tentacles  when  expanded  and  when  contracted. 
Within  the  circle  of  tentacles  is  a  small  opening,  the  mouth, 
often  difficult  to  see  in  living  animals. 

On  the  larger,  mature,  animals  will  often  be  found  pro- 
cesses resembling  the  hydra.  These  are  young  hydras,  or 


76  GENERAL  BIOLOGY 

buds,  and  -this  budding  is  the  common  method  of  repro- 
duction. What  become  of  the  buds?  Are  colonies  formed 
by  budding?  Why? 

Make  an  outline  drawing  of  the  animal  in  the  expanded 
condition,  and  one  of  the  contracted  animal. 

2.  Minute  Structure.— Place  the  dish  containing  the  hydra 
on  the  stage  of  the  compound  microscope  and  examine  with 
the  low  power;  or  place  the  hydra  on  a  slide  and  cover  with 
a  cover  glass,  supporting  the  latter  to  prevent  crushing  the 
animal.  Is  there  a  cavity  (the  enteron  or  digestive  cavity) 
in  the  animal?  Does  the  cavity  extend  into  the  tentacles? 
Sometimes  small  particles  may  be  seen  floating  in  the  cavity 
of  the  body  or  tentacles,  or  even  passing  from  the  enteron 
into  the  tentacles.  From  this  fact  what  inference  may  be 
drawn  as  to  the  structure  of  the  tentacles  and  their  mode 
of  nutrition? 

Observe  that  the  body  is  composed  of  layers  (tissues), 
an  outer  ectoderm  and  an  inner  entoderm.  Which  of  these 
layers  is  thicker?  Are  the  layers  made  up  of  cells?  In 
which  layer  is  the  coloring  matter  located?  Is  the  color 
evenly  diffused  or  is  it  segregated  into  distinct  bodies? 

Draw  a  portion  of  the  body  enlarged  to  show  the  layers; 
also  show  the  cells  if  it  is  possible  to  determine  their  outlines. 

With  the  high  power  observe  an  extended  tentacle.  Do 
you  find  ectoderm  and  entoderm?  Are  cells  present?  Note 
the  knobs  on  the  tentacles,  composed  of  oval,  transparent, 
bladder-like  bodies  or  cells.  These  are  the  stinging  cells 
(nematocysts  or  thread  cells)  which  represent  modified 
ectoderm  cells.  Where  are  the  nematocysts  most  abundant? 
Is  there  any  definite  arrangement  of  these  cells?  From 
the  outer  end  of  each  of  these  cells  projects  a  stiff  hair-like 
process,  the  trigger  or  cnidocil.  Within  the  capsule  of  the 
cell  is  a  coiled  thread  which  may  sometimes  be  made  out 


HYDRA  77 

with  the  high  power.  The  nematocysts  may  be  discharged 
from  the  body  and  the  thread  thrown  out,  this  serving  to 
secure  prey  or  to  protect  the  animal.  The  capsule  of  the 
cell  contains  a  fluid  which  escapes  through  the  thread,  and 
kills  or  paralyzes  small  animals.  By  gently  tapping  on 
the  cover  glass  above  the  animal,  or  by  introducing  beneath 
the  cover  some  irritating  fluid  as  dilute  acetic  acid  or  iodine, 
one  may  cause  a  discharge  of  the  nematocysts.  Study 
such  discharged  cells  and  observe  the  capsule,  the  thread 
and  the  barbs. 

Drawings  should  be  made  to  show  the  structures  worked 
out. 

H.  Physiology. 

1.  Irritability. — Touch  various  regions  of  the  body  with 
a  needle  and  note  results.    Is  hydra  sensitive?    Are  the 
several  parts  equally  sensitive?    Jar  the  table  or  the  slide. 
What  does  the  hydra  do? 

2.  Contractility. — Does    the    body    of    the    animal    show 
spontaneous  movements?     Do  the  tentacles  show  the  same 
properties?     Does  the  contraction  of  the  tentacles  and  body, 
or  of  all  the  tentacles,  take  place  at  the  same  time,  or  is 
there    independent    movement    and    contraction?    What 
effects  on  the  shape  of  the  body  do  the  various  movements 
produce?    Do  the   movements   seem   to  be  definitely  co- 
ordinated or  purposeful? 

3.  Locomotion.— Does  the  animal  remain  fastened  in  one 
place  in  the  aquarium  or  does  it  move  about?    On  the  out- 
side of  the  aquarium  make  a  mark  to  locate  the  position  of 
an  individual.    Make  several  observations  after  some  hours 
or  days  and  determine  whether  the  specimen  has  moved. 

4.  Heliotropism,  or  movements  in  response  to  light.    Ex- 
amine hydra  in  the  aquarium.    Are  specimens  arranged 


78  GENERAL  BIOLOGY 

or  distributed  in  any  special  relation  to  light?  Note  where 
the  specimens  are  most  abundant,  rotate  the  jar  90  to 
180  degrees  and  observe  again  after  several  days.  Have 
the  hydras  retained  the  old  position  or  are  they  in  a  new 
part  of  the  jar?  Are  they  in  the  same  position,  relative 
to  the  source  of  light,  that  they  were  before  the  jar  was 
moved? 

5.  Food  Taking.— It  is  possible  to  artificially  feed  specimens 
by  suspending  bits  of  raw  beef  within  reach  of  the  tentacles, 
or  by  placing  it  in  watch  glasses  with  hydra.    The  method 
of  capturing  prey  may  often  be  observed  by  placing  water- 
fleas  in  a  jar  or  watch  glass  containing  hydra. 

6.  Reproduction.  —  (a)  Asexual.    The    presence    of    buds 
has  already  been  noted.    How  does  the  process  take  place? 
In  what  ways  does  it  differ  from  the  process  of  fission  in  the 
protozoa?    What  becomes   of  the  bud?    What  parts   of 
the  body  are  involved  in  the  formation  of  the  bud?     DrawT. 

(6)  Sexual.— The  same  individual  usually  produces  both 
male  and  female  reproductive  products.  The  spermaries 
(testes  or  male  organs)  will  be  found,  if  present,  as  small 
conical  elevations  on  the  body  just  below  the  tentacles. 
If  these  are  mature  the  microscope  may  show  active  move- 
ments on  the  inside;  this  is  caused  by  the  swimming  of  the 
spermatozoa  within  the  testis.  If  the  testis  is  ruptured  the 
spermatozoa  may  be  seen  swimming  about  in  the  water. 
Is  there  more  than  a  single  testis  on  one  animal? 

The  ovaries  (egg-producing  or  female  organs)  usually 
develop  later  than  the  testes  and  will  therefore  not  be  found 
on  the  same  animal  that  shows  the  male  organs.  The  ovaries 
are  larger  than  the  testes,  more  spherical,  and  occur  near 
the  base  of  the  animal.  Within  the  ovary  may  sometimes 
be  seen  the  single  large  egg  or  ovum.  Is  there  more  than  a 
single  ovary  on  one  animal? 


HYDRA  79 

Which  of  the  layers  of  the  body  is  involved  in  the  form- 
ation of  the  reproductive  organs?  Make  drawings. 

III.  Sections  of  the  Body. 

On  the  slides  are  thin  sections  of  the  body  cut  transversely, 
that  is  at  right  angles  to  the  long  axis  of  the  body.  These 
sections  have  been  colored  to  render  them  more  distinct. 
Distinguish  the  ectoderm  and  entoderm.  How  are  they 
separated  ?  How  does  the  supporting  layer  which  separates 
them  differ  from  the  ectoderm  and  entoderm?  Is  the 
ectoderm  of  uniform  thickness?  Note  shape,  size  and  con- 
tents of  the  cells.  At  the  inner  ends  of  the  cells  may  some- 
times be  found  muscular  prolongations  of  the  ectoderm 
cells.  Between  the  bases  of  the  ectoderm  cells  are  smaller 
cells  not  extending  to  the  surface.  These  are  interstitial 
cells  and  from  them  arise  the  nematocysts  and  the  repro- 
ductive cells. 

Compare  the  cells  of  the  entoderm  with  those  of  the 
ectoderm  in  shape,  size  and  contents.  Look  for  gland  cells 
in  the  entoderm.  These  will  appear  as  more  deeply  stain- 
ing cells  between  the  ends  of  the  cells  which  border  on  the 
enteron ;  they  secrete  digestive  enzymes. 

Draw  a  portion  of  the  section  much  enlarged  showing, 
especially,  the  cell  structure. 


HYDROID. 

PENNARIA  TIARELLA. 

PENNARIA  is  a  colonial,  marine  animal  growing  on  sea- 
weed, on  the  piles  of  docks,  and  in  similar  places.  It  is 
a  relative  of  the  fresh  water  polyp,  which  has  already  been 
studied. 

1.  The  Colony.— Examine  a  portion  of  the  colony  with  a 
lens,  and  note  that  it  consists  of  a  stem  with  branches,  each 
terminated  by  a  flask-shaped  body.    This  body  is  called 
the  hydranth  or  zob'id,  and  represents  a  single  individual  of 
the  colony  comparable  to  an  entire  hydra.    Are  all  hydranths 
alike  in  form  and  size?    What  is  the  general  form  and  char- 
acter of  the  colony?    Is  there  any  definite  order  to  the 
branching?    How    is    the    colony    attached?    This    basal 
portion,  the  hydrorhiza,  is  really  a  creeping  portion  of  the 
stem.    Do  young  stems  arise  from  it?    In  the  stem  the 
central  axis,  which  is  the  fleshy  part  of  the  animal,  is  called 
the  cosnosarc,  and  it  is  surrounded  by  a  horny,  dark  colored, 
protective  sheath,  the  perisarc.     Does  the  perisarc  cover 
all  parts  of  the  colony? 

Make  a  drawing  of  the  colony  about  twice  natural  size, 
showing  its  habit  of  growth. 

2.  Hydranth.— Place  a  portion  of  a  colony  in  a  watch 
glass  or  on  a  slide  and  with  the  low  power  of  the  compound 
microscope  make  out  the  form  and  shape  of  a  single  hydranth. 
Are  tentacles  present?    How  many?    How  arranged?  Are 
the  tentacles  alike?     If  more  than  one  kind  is  found  note 


HYDRO  ID  81 

the  points  of  difference.  A  mouth  is  present  at  the  tip  of 
the  hydranth,  but,  unless  open,  will  not  readily  be  found. 
Is  there  a  cavity  present  as  there  was  in  hydra?  Does  it 
extend  into  the  stem  and  the  tentacles? 

Make  an  enlarged  drawing  of  a  single  hydranth  with  a 
portion  of  the  adjacent  stem. 

With  the  high  power  examine  the  different  tentacles  of  a 
hydranth  with  care  and  make  out  the  ectoderm  and  the 
entoderm,  and  the  boundaries  of  the  cells.  Are  the  tentacles 
alike  in  the  arrangement  and  relative  size  of  the  layers  and 
of  the  cells?  Are  they  hollow  as  in  Hydra?  Look  for 
bladder-like,  oval,  transparent  cells  in  the  tentacles  (the 
nematocysts  or  stinging  cells).  Note  their  size  and  arrange- 
ment. 

Make  drawings  of  portions  of  the  different  tentacles  as 
seen  under  the  high  power. 

3.  Reproduction.— Reproduction  in,  Pennaria,  and  in  the 
hydroids  generally,  is  of  two  kinds,  asexual  and  sexual. 

(a)  Asexual.— The  entire  colony  is  produced  by  budding. 
Look  for  buds  on  the  sides  of  the  stem,  just  below  the  hy- 
dranths.  These  buds  produce  new  hydranths,  and  there- 
by increase  the  size  of  the  colony.  Other  buds  are  formed 
on  the  sides  of  the  hydranths,  these  are  called  medusae  and 
when  they  are  full  grown  they  separate  from  the  hydranth 
and  float  freely  in  the  water.  They  have  the  power  of 
locomotion  and  swim  about  as  distinct  individuals.  If 
possible  make  out  the  structure  of  the  larger  ones. 

(6)  Sexual.— The  medusae  formed  by  budding  from  the 
sides  of  the  hydranths  are  sexual  individuals,  and  they  pro- 
duce either. eggs  or  spermatozoa.  The  eggs  and  the  sper- 
matozoa are  ripe  when  the  medusae  are  liberated,  and  are 
cast  into  the  water  where  fertilization  occurs.  The  fertilized 
egg  develops  into  a  free  swimming  larva  which  after  a  time 


82  GENERAL  BIOLOGY 

settles  down,  fastens  itself  to  some  body  and  grows  into  a 
polyp  or  hydranth,  which  by  budding  produces  a  new 
hydroid  colony. 

The  life  cycle  of  this  animal  is,  therefore,  somewhat  com- 
plicated and  involves  an  alternation  of  generations.  A 
hydroid,  we  have  seen,  by  asexual  budding  produces  a 
medusa,  and  this  through  sex  cells  gives  rise  to  a  hydroid 
colony.  There  is,  therefore,  an  alternation  of  the  asexual 
and  the  sexual  methods  of  reproduction. 


HYDROID. 

OBELIA  OR  CAMPANULARIA. 

THIS  hydroid  has  about  the  same  mode  of  life  and  lives 
in  the  same  places  as  Pennaria. 

With  a  lens  examine  a  colony  making  out  the  stem,  branches 
hydrorhiza,  and  hydranths.  Compare  with  Pennaria  on 
these  points.  Make  a  drawing  of  the  colony  showing  its 
habit  of  growth. 

With  the  compound  microscope  examine  the  colony  more 
carefully  and  discover  whether  there  is  a  perisarc  as  in 
Pennaria.  Does  it  differ  from  that  in  the  other  hydroid? 
In  these  hydroids  the  perisarc  at  the  end  of  each  branch 
widens  out  to  form  a  funnel-shaped  enlargement  (the  hy- 
drotheca)  which  may  entirely  enclose  the  hydranth.  Why 
are  some  hydranths  entirely  enclosed  within  hydrothecse, 
while  others  extend  beyond  this?  The  perisarc  around  the 
stem,  and  around  the  hydranth  as  well,  is  of  a  horny  con- 
sistency and  has  been  secreted  by  the  ectoderm  cells  of  the 
coenosarc.  When  this  was  taking  place  the  ectoderm  was 
in  contact  with  the  perisarc.  Examine  the  colony  closely 
and  find  different  stages  in  the  formation  of  a  hydro theca. 

Compare  the  hydranth  with  that  of  Pennaria  in  size, 
shape  and  structure.  How  many  tentacles  are  there?  How 
are  they  arranged?  Are  they  alike?  Note  the  mouth, 
which  is  at  the  end  of  an  enlargement,  the  proboscis  or 
hypostome.  How  is  the  hydranth  supported  in  the  hy- 
drotheca? 


84  GENERAL  BIOLOGY 

Make  an  enlarged  drawing  of  an  expanded  and  another 
of  a  contracted  hydranth. 

Examine  a  tentacle  with  the  high  power  and  find  the 
ectoderm  and  the  entoderra  layers,  and  the  outlines  of  the 
cells  of  these  layers.  How  does  the  tentacle  differ  from 
that  of  hydra,  and  from  that  of  Pennaria?  Are  nematocysts 
present?  Where  are  they  located?  Make  a  drawing  of 
the  basal  portion  of  a  tentacle  showing  the  cell  outlines. 

Look  for  branches  which  have  an  elongate,  rather  club- 
shaped,  enlargement  of  the  perisarc.  The  ccenosarc  within 
will  show  no  tentacles  and  no  mouth.  This  is  the  gonangium, 
or  receptacle  containing  reproductive  buds.  The  ccenosarc 
forms  a  central  core  the  blastostyle,  which  is  a  modified 
hydranth  body;  from  the  sides  of  this  are  budded  off  small 
medusae.  .  These  medusae  become  free,  escape  from  the 
gonangium  and  swim  away.  Unlike  Pennaria  the  medusae 
of  Obelia  are  not  sexually  mature  at  the  time  of  escape,  but 
the  eggs  or  spermatozoa  are  formed  only  after  several  weeks 
of  active  life.  The  eggs  -develop  into  new  hydroids  as  in 
Pennaria,  the  same  alternation  of  generations  being  shown. 

Draw  a  gonangium. 

Campanularia  differs  from  Obelia  chiefly  in  its  repro- 
ductive process.  In  Campanularia  no  medusae  are  formed, 
but  within  the  gonangium  eggs  or  sperms  are  produced. 
Fertilization  occurs  within  the  gonangium  and  the  egg 
develops  into  a  free  swimming  larva  (planula)  which  escapes 
from  the  gonangium.  The  planula  fixes  itself  and  trans- 
forms directly  into  a  polyp,  which  buds  and  produces  a 
colony. 


THE  MEDUSA. 

GONIONEMUS  MURBACHII. 

THE  medusae  formed  by  the  hydroids  studied,  Pennaria 
and  Obelia,  are  so  small  that  their  structure  can  be  made 
out  only  with  some  difficulty.  Therefore,  a  larger  medusa  is 
taken  as  a  type  for  study.  Although  Gonionemus  does  not 
belong  to  the  same  order  as  the  hydroids  described,  and  the 
hydroid  stage -is  greatly  reduced,  it  has  about  the  same 
structure  as  the  medusae  which  are  formed  from  these  hy- 
droids. 

Place  specimens  in  a  watch  glass  with  water  and  examine 
with  a  lens.  The  umbrella  or  bell  shape  is  rather  character- 
istic of  all  medusae.  The  external  convex  part  is  called  the 
exumbrella  or  aboral,  and  the  concave  part  is  the  subumbrella 
or  oral  side.  The  under  part  of  the  medusa  is  partly  closed 
by  a  membrane  called  the  velum,  or  veil.  Where  are  the 
tentacles?  Are  they  alike.  How  many  are  there?  Are 
they  regularly  arranged?  Are  nematocysts  present?  If 
so  note  their  arrangement.  Near  the  tip  of  the  tentacle  is 
an  adhesive  or  muscular  pad  used  by  the  medusa  for  hold- 
ing against  some  object. 

Within  the  subumbrellar  space  note  the  central  hanging 
sac,  the  manubrium  or  stomach.  Is  a  mouth  present?  A 
gastric  cavity?  How  does  the  mouth  differ  from  that  of 
the  hydroids?  Note  the  radial  canals,  delicate  tubes  which 
extend  outward  from  the  center  of  the  bell.  How  many 
canals  are  there?  Is  the  number  the  same  in  all  specimens? 


86  GENERAL  BIOLOGY 

Are  they  symmetrically  arranged?  Do  they  join  the  gastric 
cavity?  The  canals  extend  to  the  periphery  of  the  bell  and 
open  into  a  marginal  canal  which  extends  completely  around 
the  medusa  and  communicates  with  the  hollow  tentacles. 
Why  is  there  such  a  system  of  canals  in  the  medusa  and  not 
in  the  polyp? 

Hanging  from  the  under  surface  of  the  canals  are  large, 
convoluted,  ribbon-like  organs,  brownish  in  color.  These 
are  the  reproductive  organs.  The  medusae  are  males  or 
females,  but  the  reproductive  organs  look  alike. 

Draw  the  entire  medusa  from  the  side;  also  from  the 
oral  aspect.  Draw  a  portion  of  a  tentacle  showing  the 
arrangement  of  the  nematocysts,  and  the  adhesive  organ. 


EARTHWORM. 

LUMBRICUS    SP. 

PLACE  the  worm  in  the  dissecting  pan  with  enough- 
water  to  cover  it.  What  is  the  form  of  the  body?  Does 
it  vary  in  any  part?  What  is  the  color?  Does  it  vary? 
Has  the  body  any  protective  covering?  Are  there  append- 
ages such  as  legs?  Are  there  gills  or  other  respiratory  struc- 
tures? Are  there  organs  of  hearing  or  sight? 

I.  External  Anatomy. 

1.  General   Features.— Notice    the    regular    segmentation 
of  the  body  into  a  series  of  rings,  somites  or  metameres. 
How  many?    Compare  with  the  number  found  on  other 
specimens  and  indicate  whether  it  is  constant.    Are  the 
somites  of  the  same  size  and  form  throughout?     Notice 
the  prostomium  projecting  from  the  first  somite,  and  the 
clitellum  or  girdle  about  one-third  of  the  way  back  from  the 
anterior   end.     Which   segments   make   up   the   clitellum? 
In  what  way  does  this  part  of  the  body  differ  from  the  rest? 
The  clitellum  is  composed  of  glands  in  the  skin  which  secrete 
a  substance  to  form  the  cocoon  or  case  in  which  the  eggs 
are  deposited. 

2.  Regions  of  the  Body.  — Distinguish  an  anterior  or  head 
end,  and  a  posterior  or  tail  end.     Is  there  a  definite  head? 
How  are  the  dorsal  and  ventral  sides  differentiated?     Are 


88  GENERAL  BIOLOGY 

these  distinctions  equally  marked  in  all  parts  of  the  body? 
Are  the  two  sides  of  the  animal  alike?  If  so,  it  is  said  to 
be  bilaterally  symmetrical. 

3.  Setae  are  short,  horny  spines  embedded  in  the  body 
wall  but  projecting  a  little.    They  aid  in  locomotion.    They 
may  be  felt  by  rubbing  the  finger  over  the  ventral  surface 
of  the  body.    If  this  region  is  examined  with  a  lens  the 
seta?  will  be  seen  as  tiny  brown  spots.    How  many  are  there 
on  each  somite  ?    How  are  they  arranged  ? 

4.  Openings  of  the  Body.— The  mouth  will  be  found  on 
the  ventral  side  of  the  body  at  the  first  somite.    What  is 
the  position  of  the  mouth  relative  to  the  prostomium?    At 
the  end  of  the  last  segment  of  the  body  is  the  anus,  the 
posterior  end  of  the  digestive  tube.    On  the  ventral  side 
of  the  fifteenth  somite  are  the  openings  of  the  testes,  called 
the  sperm  ducts,  one  on  either  side  surrounded  by  swollen 
lips.    The  ovaries  open  through  the  oviducts  on  the  ventral 
side  of  the  fourteenth  somite,  but  they  are  not  surrounded 
by  swollen  lips.    The  openings  to  the  sperm  receptacles, 
of  which  there  are  two  pairs,  are  situated  in  the  grooves 
between  the  ninth  and  tenth  and  the  tenth  and  eleventh 
somites,  and  are  on  the  sides  of  the  animal  in  the  same  line 
as  the  lateral  rows  of  setae. 

The  openings  of  the  excretory  organs  are  found  in  each 
segment  on  the  ventral  surface  a  little  anterior  to  the  outer 
seta  of  the  ventral  row.  They  are  not  very  plain,  but  with 
a  lens  will  usually  show  well  on  some  somites.  The  dorsal 
pores,  which  communicate  with  the  ccelomie  cavity,  are  in 
the  middorsal  line  and  open  in  the  grooves  between  the 
somites. 

Draw  the  anterior  and  the  posterior  parts  of  the  body 
to  show  all  that  you  have  observed. 


EARTHWORM  89 

II.  Internal  Anatomy. 

With  the  scissors  cut  through  the  body  wall  in  the  mid- 
dorsal  line  from  about  the  middle  of  the  body  to  the  third 
somite,  taking  care  not  to  cut  the  viscera  lying  beneath. 
Carefully  cut  the  membranous  partitions,  the  septa,  at  the 
points  where  they  join  the  body  wall  and  pin  back  the  flaps 
of  the  latter.  Notice  that  the  body  wall  forms  a  tube  in 
whose  cavity,  the  body  cavity  or  coelom,  lies  another  tube, 
the  alimentary  or  digestive  tube:  also  that  the  septa  divide 
the  body  cavity  into  smaller  chambers.  What  relation  is 
there  between  the  septa  and  the  external  segmentation? 
Observe  first  the  alimentary  canal  which  extends  through 
the  animal;  also  several  pairs  of  conspicuous  white  bodies 
near  the  anterior  end.  The  latter  are  the  sperm  sacs. 

1.  Circulatory  System.— This  system  is  a  series  of  closed 
tubes  consisting  of  several  longitudinal  vessels  and  many 
circular  vessels  connecting  them.    The  largest  of  the  longitu- 
dinal vessels,   the  dorsal  vessel,  is  in  the  middorsal  line 
against   the   alimentary   canal.    Beneath   the   intestine   is 
the  ventral  vessel  which  will  be  seen  later  when  the  alimentary 
canal  is  removed,  and  ventral  to  the  nerve  cord  is  a  third 
longitudinal    vessel,    the    subneural    vessel.    The    circular 
vessels  extend  between  the  dorsal  and  the  ventral  vessels 
and  occur  in  pairs.    Five  pairs  of  these  circular  vessels  in 
the  anterior  region  (somites  seven  to  eleven)  are  very  large, 
and  being  contractile  are  called  hearts;   the  dorsal  vessel  is 
also   contractile.     Carefully   dissect   away   the   septa   and 
expose  the  hearts. 

2.  Reproductive  System.— The  earthworm  is  a  hermaph- 
rodite animal  containing  both  the  male  and  the  female 
organs  in  a  single  individual. 


90  GENERAL  BIOLOGY 

(a)  The  Male  Organs.  —The  sperm  sacs,  or  seminal  vesicles, 
lying  in  somites  ten  to  fourteen  are  large  white  organs,  com- 
posed of  several  lobes.  In  these  the  spermatozoa  under- 
go a  portion  of  their  development.  There  are  two  pairs  of 
spermaries  or  testes  enclosed  within  the  seminal  vesicles, 
but  they  are  so  minute  as  to  render  their  dissection  very 
difficult. 

(6)  The  Female  Organs.— The  sperm  receptacles  are  two 
pairs  of  spherical,  whitish  or  yellowish  sacs  beneath  the 
sperm  sacs,  in  the  ninth  and  tenth  somites.  In  these  re- 
ceptacles the  spermatozoa  received  from  another  worm  are 
stored,  and  from  them  the  sperms  are  passed  into  the  egg 
case  in  which  the  eggs  are  laid.  The  ovaries  (one  pair), 
are  small  organs  near  the  median  line,  attached  to  the 
anterior  septum  of  the  thirteenth  somite.  They  will  be 
rather  hard  to  find.  Posterior  to  them  are  funnel-shaped 
openings  which  lead  into  the  oviducts,  and  these  in  turn 
open  to  the  exterior  at  the  fourteenth  somite. 

Earthworms  meet  and  pair  at  night  in  May  and  June, 
and  the  sperm  receptacles  of  each  are  filled  writh  spermatozoa 
from  the  other  worm.  They  separate  and  later  the  girdle 
secretes  a  fluid  which  hardens  and  forms  a  tough  cylindrical 
membrane  or  cocoon  about  the  body.  The  cocoon  is  moved 
forward  and  as  it  passes  the  fourteenth  somite  eggs  pass 
into  it,  and  at  somites  ten  and  eleven  spermatozoa  enter 
and  the  fertilization  of  the  eggs  takes  place.  The  cocoon 
passes  over  the  anterior  end  of  the  animal  and  drops  to  the 
ground,  the  ends  close  and  within  this  free  capsule  the  develop- 
ment of  the  young  worms  takes  place. 

3.  Digestive  System.— Carefully  remove  the  sperm  sacs 
and  the  septa  in  the  anterior  portion  of  the  body,  exposing 
the  tube-like  esophagus.  Find  the  following  parts :  pharynx 
(somites  twyo  to  five),  esophagus  (six  to  thirteen),  crop  (four- 


EARTHWORM  91 

teen  to  sixteen),  gizzard  (seventeen  to  ninteen),  stomach- 
intestine  extending  to  the  posterior  end  of  the  body.  In 
the  walls  of  the  esophagus  in  somites  ten  to  twelve  are 
three  pairs  of  small  sacs  or  pouches,  the  calciferous  glands, 
which  open  into  the  esophagus. 

Compare  the  several  organs  in  size,  color,  thickness  of 
walls,  the  lining  of  each.  •  In  the  stomach-intestine  note 
the  dorsal  infolding,  the  typhlosole.  Note  also  the  delicate 
muscle  fibers  wyhich  extend  from  the  body  wall  to  the  pharynx. 
What  possible  function  might  these  serve? 

4.  Excretory  System.— This  consists  of  paired  segmental 
organs,  the  kidneys  or  nephridia,  which  are  made  up  of  coiled 
tubes  held  closely  together  and   suspended  close  to  the 
ventral  and  lateral  body  wall.     Remove  one  of  the  nephridia, 
place  on  a  slide,  and   examine  with  the  compound  micro- 
scope. 

Make  a  large  drawing  and  in  it  show  all  the  internal 
structures  that  you  have  observed. 

5.  Nervous    System.— Dissect    and   remove    the    anterior 
end  of  the  alimentary  canal  except  the  pharynx.    This  will 
expose  the  white  nerve  cord,  lying  in  the  median  ventral  side 
of  the  body  cavity.     Immediately  over  this  is  the  ventral 
bloodvessel,   one  of  the  main  longitudinal  trunks  of  the 
circulatory  system. 

Examine  with  the  lens  and  notice  that  there  are  small 
swellings,  the  ganglia.  How  many  in  each  somite?  Are 
there  nerves  coming  out  from  the  cord?  How  many  in 
each  somite?  Do  they  come  from  the  ganglia,  or  from  be- 
tween the  ganglia?  Carefully  expose  the  cord  anteriorly, 
pushing  the  pharynx  to  one  side,  and  on  the  dorsal  side  of 
the  pharynx  will  be  found  the  cerebral  ganglia  or  brain. 
How  is  this  connected  with  the  ventral  cord?  Make  a 
large  drawing  of  the  brain  and  several  of  the  ganglia  and 
their  nerves. 


92  GENERAL  '  BIOLOG  Y 

HI.  Microscopic  Anatomy.     (Histology.) 

On  the  slides  furnished  are  sections  across  the  body  in  the 
region  of  the  stomach-intestine,  and  these  are  stained  in 
drder  that  the  various  tissues  may  be  more  plainly  seen. 

1.  Study  the  entire  section  and  identify  the  following 
structures:     (a)  body  wall  and   its  layers;    (6)  ccelom;  (c) 
intestine;     (d)  dorsal    and    ventral   bloodvessels;     (e)  nerve 
cord.    Other  organs  likely  to  be  found  are  setse,  excretory 
organs,  septa. 

Make  a  drawing  of  the  entire  section  showing  all  the 
parts  mentioned,  but  not  attempting  to  indicate  the  cells 
which  make  up  the  tissues. 

2.  Body  Wall.— With  the  high  power  study  the  body  wall 
and  make  out  the  cuticle,  epidermis,  circular  muscles,  longi- 
tudinal muscles,  and  a  delicate  layer  of  cells  lining  the  ccelomic 
cavity,  the  peritoneum.    Make  out  the  cellular  character 
of  the  various  layers  and  make  a  drawing  of  a  small  segment 
of  the  body  wall    showing  the   layers  and  the  cells  which 
compose  them. 

3.  Intestine.— Are  the  walls  of  the  same  thickness  through- 
out?   The  dorsal  infolding  of  the  intestinal  wall  is  called 
the  typhlosole.     How  much  of  the  cavity  of  the  intestine 
does  it  occupy?    Make  a  careful  study  of  the  tissues  and 
cells  of  the  intestinal  wall;    from  without  inward  these  are 
as  follows:     Chlorogogue,  pear-shaped  cells  rather  loosely 
arranged;     between  the  bases  of  the  chlorogogue  cells  are 
small  scattered  fibers,  the  longitudinal  muscle;    a  definite 
and  clearly  marked  circular  muscle  layer;  inside  of  this  there 
may  be  spaces,  the  bloodvessels  of  the  intestine;   lining  the 
intestine  is  a  thick  layer  of  ciliated,  columnar  epithelium. 

Draw  a  portion  of  the  wall  as  seen  with  the  high  power, 
showing  the  cells  of  each  layer. 


EARTHWORM  93 

4.  Nerve  Cord.— What  is  the  shape  of  the  cord  as  seen  in 
section?  If  nerves  are  present  notice  the  place  and  the 
manner  in  which  they  emerge  from  the  cord.  The  cord  is 
enclosed  within  a  connective  tissue  sheath,  scattered  through 
which  are  many  muscle  fibers.  Are  these  circular  or  longi- 
tudinal muscles?  Also  within  this  sheath  are  located  three 
longitudinal  bloodvessels,  ventrally  the  subneural,  at  the 
sides  the  lateral-neural  vessels.  The  pear-shaped  cells  in 
the  cord  are  the  nerve  cells,  and  the  delicate  fibers  that  seem 
to  be  prolongations  of  the  cells  are  the  nerves.  Are  nuclei 
present  in  the  nerve  cells?  Are  the  nerve  cells  abundant? 
Where  are  they  located?  At  the  dorsal  side  of  the  cord  are 
three  areas  that  are  called  giant  fibers.  Filling  up  the  bulk 
of  the  cord  are  connective  tissue  fibers. 

Draw  an  enlarged  section  of  the  entire  cord,  showing  the 
points  observed. 

IV.  Physiology. 

Make  the  following  study  of  the  living  worm. 

1.  Movements.— Place  the  worm  on  a  damp,  rough  sur- 
face, as  filter  paper,  and  observe  the  kinds  of  movements 
and  the  way  they  are  produced.    By  what  means  does  the 
worm  move  from  place  to  place?     Can  it  climb  over  ob- 
structions?   Place  the  worm  on  a  moist,  perfectly  clean 
glass.    Explain  the  behavior  observed. 

2.  Sensitiveness.— With  a  bristle  or  a  blunt  instrument, 
touch  the  worm  in  different  places.    What  regions  are  the 
most  sensitive?    How  is  this  indicated?    Try  the  effect 
of  stimuli  such  as  warmth  of  the  breath,  sunlight,  vapor  of 
ammonia  or  chloroform,   dilute  acetic  acid.    Record  the 
results  obtained. 

3.  Circulation.— If  the  body  wall  is  not  too  thick,  nor  too 
heavily  pigmented,  the  pulsations  of  the  dorsal  bloodvessel 


94  GENERAL  BIOLOGY 

may  be  seen  through  the  wall.  In  what  direction  is  the 
blood  flowing?  Further  observations  on  circulation  may 
be  made  upon  a  worm,  anesthetized  with  chloroform,  which 
has  been  opened  to  expose  the  bloodvessels.  Observe  the 
contraction  of  the  dorsal  vessel  and  the  hearts,  also  note 
the  delicate  bloodvessels  upon  the  various  organs. 


SAND  WORM. 

NEREIS  VIRENS. 

THESE  animals  are  found  on  the  seashore  in  burrows  of 
sand  and  mud  near  low  water  mark. 

I.  External  Anatomy. 

1.  General  Features.— Is  there  a  differentiation  into  dorsal 
and    ventral?    Anterior    and    posterior?     How    are    these 
regions    distinguished?     Compare    writh    the    earthworm. 
How  many  somites?     Is  the  number  as  variable  as  in  the 
earthworm?     Are  the  somites  alike  in  size  and  form?     Is 
the  body  divided  into  regions? 

2.  Head.— In  the  head   there   are   the   following  parts: 
A  triangular  prostomium  which  bears  on  its  anterior  margin 
a  pair  of  short  tentacles.     On  each  side  there  is  a  fleshy 
palp.     The  four  eyes  are  on  the  dorsal  surface  of  the  pros- 
tomium, and  are  sometimes  hard  to  find.    The  peristomium 
is  the  ring  around  the  mouth.     Compare  it  with  the  first 
body  somite.    It  bears  four  lateral  or  peristomial  tentacles 
on  either  side.    Note  the  large  jaws  which  may  be  partly 
extended  from  the  pharynx. 

Make  a  drawing  showing  the  head  and  several  of  the 
body  somites. 

3.  Appendages.— On  each   side   of  most  of  the   somites 
there  is  an  appendage  called  a  parapodium.     In  each  para- 
podium  there  are  the  following  parts:     A  dorsal  blade,  the 
gill,  which  bears  a  short  cirrus;   and  a  ventral  blade  consist- 


96  GENERAL  BIOLOGY 

ing  of  two  fleshy  lobes.  There  is  also  a  ventral  cirrus.  From 
each  blade  a  number  of  setae  arise  in  bundles.  In  each 
blade  there  is  embedded  a  short -stiff  rod,  the  aciculum, 
which  serves  to  support  the  appendage.  Examine  the  last 
body  somite  and  note  any  differences  from  the  other  somites. 
Make  an  enlarged  drawing  of  a  single  parapodium. 

n.  Internal  Anatomy. 

Open  the  worm  in  the  same  manner  as  the  earthworm. 
Note  the  body  wall,  the  ccelom,  the  septa,  and  observe  any 
differences  from  the  conditions  present  in  the  other  worm. 

The  digestive  system  has  a  large  muscular  pharynx,  in 
which  are  the  large  jaws  noted  above,  and  also  some  small 
teeth  covering  the  walls.  Can  you  account  for  the  differences 
in  the  pharynx  of  this  worm  and  the  earthworm?  The 
pharynx  opens  into  a  large  crop,  into  which  also  empty 
digestive  glands.  Was  there  anything  corresponding  to 
the  digestive  glands  in  the  earthworm?  The  rest  of  the 
digestive  tube  is  composed  of  the  straight  stomach-intestine. 

The  pharynx  is  protrusible  and  there  are  protractor  and 
retractor  muscles  to  operate  the  proboscis  and  the  jaws. 

The  circulatory  and  excretory  systems  are  much  like 
those  of  the  earthworm,  though  they  are  not  so  large  nor 
so  easily  worked  out. 

In  the  sand  worm  the  sexes  are  separate  and  the  repro- 
ductive organs  are  present  only  at  the  breeding  season. 
A  portion  of  the  tissue  lining  the  ccelom  produces  sperms 
or  eggs  at  this  time.  When  the  reproductive  products  are 
ripe  the  body  wall  is  ruptured  and  the  germ  cells  escape 
into  the  water  where  the  fertilization  takes  place..  Unless 
the  worms  were  obtained  during  the  breeding  season  the 
reproductive  organs  will  not  be  found. 


SAND  WORM  97 

The  digestive  tube  should  be  removed  to  expose  the  nerve 
cord,  which  is  present  on  the  ventral  body  wall  as  in  the 
earthworm.  Compare  the  cord  with  that  of  the  earth- 
worm. Are  ganglia  present?  Describe  the  arrangement 
and  distribution  of  ganglia  and  nerves.  Is  there  a  com- 
missure about  the  pharynx  and  a  brain  or  cerebral  ganglia 
on  the  dorsal  side? 

On  account  of  the  numerous  sense  organs  on  the  head 
the  brain  is  larger  and  there  are  more  nerves  coming  from 
it  than  in  the  earthworm.  The  brain  lies  very  close  to  the 
surface  and  is  difficult  to  expose  without  injury. 

Make  drawings  to  represent  the  various  internal  systems. 


THE  FERN. 

PTEBIS  AQUTLINA. 

THE  common  brake  is  widely  distributed,  growing  in 
nearly  all  damp,  shady  places.  If  the  structure  of  the 
entire  plant  is  to  be  studied,  they  should  be  collected  and 
used  fresh  or  else  preserved  in  formalin.  Early  summer 
is  the  best  time  for  the  collection,  though  the  plants  will  be 
in  fairly  good  condition  in  the  early  fall.  For  the  histological 
study  the  rhizome  must  be  sectioned  in  the  usual  way. 
The  sections  may  be  stained,  but  some  of  the  tissues  will 
show  well  without  stain. 

This  organism  is  composed  of  organs  which  are  partly 
underground  and  partly  above  ground,  the  former  com- 
posed of  the  underground  stem,  or  rhizome,  and  roots  which 
serve  to  absorb  water  and  salts  from  the  soil.  From  the 
rhizome  leaves,  or  fronds,  extend  into  the  air  as  the  chlorophyll 
bearing  parts,  with  supporting  and  nutritive  organs. 

The  leaf  consists  of  a  main  stem  or  stalk  divided  into 
leaflets,  or  pinnae  and  pinnules.  It  is  in  the  leaf  that  the 
food  is  elaborated  from  simple  compounds  and  elements 
.through  the  activity  of  the  chlorophyll  bodies,  or  chloro- 
plasts,  which  are  but  modified  masses  of  protoplasm.  Here 
are  also  found  organs  of  reproduction. 

The  main  object  in  the  study  here  outlined  is  an  insight 
into  the  fundamental  structure  of  a  plant,  its  parts,  their 
relations  and  functions.  A  further  aim  is,  by  rough  com- 
parison, to  discover  any  similarities  of  structure  and  organi- 


THE  FERN  99 

zation,  between  plants  and  animals,  as  well  as  to  demon- 
strate the  contrasts  of  structure  and  their  relations  to  the 
markedly  different  functions  to  be  performed. 

I.  Leaf  or  Frond. 

1.  The  stalk  or  stipe  bears  the  expanded,  foliaceous  part 
with  its  numerous  lobes,  pinnae,  which  are  further  subdivided 
into  ultimate  leaflets,  pinnules.     Note  whether  there  are, 
on  any  part  of  the  frond,  hair-like  elements,  trichomes. 

2.  Midrib  and  veins  are  special  structures  forming  a  sort 
of  framework  of  the  leaf.    Are  midrib  and  veins  derived 
from  the  stalk  and  connected  with  it?     Do  they  sustain 
any  relation  to  the  lobings  of  the  leaf?     Not  only  do  these 
form  a  structural  framework,  they  are  also  paths  for  the 
movements  of  liquids. 

3.  Histology  of  the  Leaf.— From  portions  of  the  leaf  re- 
move bits  of  the  epidermis  and  examine  with  both  low  and 
high  power  and  study  the  structure.    Are  cells  present? 
Observe    the    shape,    structure,    contents.    Compare    the 
epidermis  from  both  sides  of  a  leaflet  and  note  likenesses  and 
differences.    Look  for  minute  pores,  stomata,  and  note  upon 
which  side  of  the  leaflet  they  occur.    They  are  the  so- 
called  breathing  pores,  and  relate  to  the  functions  of  trans- 
piration and  respiration.    Sketch  cells  of  the  epidermis. 

II.  Rhizome. 

Study  sections  of  the  rhizome  and  note  the  varied  aspects 
of  different  regions,  which  indicate  the  several  tissues,  or 
tissue  systems,  of  the  rhizome.  On  the  outside  is  the  cortex, 
made  of  an  outer  layer  of  epidermis,  lifeless  and  protective, 
and  beneath  this  a  subepidermis  whose  cell  walls  are  hard 
and  woody,  but  which  contain  living  protoplasm. 


100  GENERAL  BIOLOGY 

Make  a  careful  drawing  of  some  of  the  cells  of  this  region. 

Within  the  cortex,  and  making  up  the  greater  part  of 
the  rhizome,  is  the  living  tissue,  called  parenchyma  or  pith. 
What  is  the  shape  of  the  cells?  How  are  they  joined  to- 
gether? Is  there  protoplasm  within  these  cells?  Are  there 
any  bodies  within  the  protoplasm  which  might  be  dead 
substances  as  food?  If  fresh  sections  are  available  treat 
with  iodine  solution  and  determine  whether  starch  is  present. 

Make  drawings  of  the  parenchyma  cells. 

Scattered  through  the  parenchyma  are  two  large  masses 
and  several  smaller  masses  of  brownish  cells,  the  sclerenchyma. 
Is  there  any  definite  arrangement  to  these  masses?  Com- 
pare the  shape  and  the  grouping  of  the  cells  with  that  of 
the  parenchyma.  Is  it  similar  to  the  parenchyma?  Is 
the  cell  wall  like  that  of  the  parenchyma  cells?  Is  proto- 
plasm present?  Do  these  cells  resemble  more  the  paren- 
chyma or  the  cortex?  These  cells  are  developed  from  the 
parenchyma  cells  by  the  formation  of  lignin  or  wood,  and 
they  serve  to  form  a  framework  for  rigidity  and  support. 
Is  the  structure  apparently  adapted  for  this?  Why  would 
the  parenchyma  not  serve  this  purpose. 

Make  a  drawing  of  the  cells  of  this  tissue. 

Oval  or  circular  patches  are  scattered  through  the  rhizome 
and  are  known  as  nbro-vascular  bundles.  These  bundles 
anastomose  and  form  a  sort  of  network  through  the  rhizome 
and  frond,  through  which  liquids  are  conducted  from  place 
to  place.  Study  one  of  the  bundles  carefully  and  make 
out  the  following: 

1.  Bundle  sheath,  around  the  bundle. 

2.  Phloem  sheath,  parenchyma  like  cells  containing  proto- 
plasm and  starch. 

3.  Bast  Fibers.    Small  cells  with  protoplasm. 

4.  Sieve  Tubes.    Large  thin  walled  cells. 


THE  FERN  101 

5.  Tracheids.    Very  large  thick  walled,  empty  cells  or 
tubes. 

6.  Spiral  Vessels.     Smaller  empty  cells. 

The  functions  of  the  different  portions  of  the  bundles 
must  be  determined  by  reference  to  text-books. 

Make  drawings  showing  the  different  cells  of  the  bundles. 

If  possible  examine  longitudinal  sections  and  identify 
the  tissues  observed  in  the  transverse  sections. 

In  a  very  general  way  compare  the  organization  and 
structure  of  the  fern  with  that  of  the  earthworm  or  other 
animal.  Are  there  similar  functions  in  the  two,  if  so  what 
are  they,  and  what  organs  perform  them?  What  organ 
system  has  the  animal  that  is  lacking  in  the  plant  and  vice 
versa?  In  what  are  the  tissues  alike,  in  what  different?  In 
what  respects  are  the  cells  of  these  tissues  alike,  in  what 
different? 

m.  Reproduction. 

Ferns  present  conspicuous  sexual  and  asexual  cycles,  or 
alternation  of  generations.  Of  these  the  ordinary  fern  plant 
is  the  asexual  generation  or  sporophyte,  producing  within 
certain  organs  of  the  leaf  numerous,  non-sexual  spores. 
These  germinating  give  rise  to  inconspicuous,  sexual  plants 
forming  the  sexual  generation  or  gametophyte,  which  form 
the  sex  cells. 

1.  Sporophytic  Organs. — Examine  mature  leaves  for  the 
spore-producing  structures,  sporangia,  which  are  borne  along 
the  margins  of  the  leaflets.  Observe  the  membrane,  indusium, 
which  encloses  and  protects  the  sporangia.  With  needles 
carefully  dissect  off  the  coverings  and  observe  the  sporangia. 
Describe  the  shape,  color  and  size  of  these  capsules.  Can 
you  find  any  variations?  If  so,  how  do  you  account  for 
such? 


102  GENERAL  BIOLOGY 

Examine  some  of  the  sporangia,  and  work  out  the  follow- 
ing parts,  using  the  high  power  where  necessary: 

(a)  The  Stalk  or  Pedicle. —What  is  its  shape  and  structure ? 
(6)  The  Capsule  which  contains  the  spores.  What  is 
its  shape  and  structure?  Note  especially  the  annulus, 
or  crescent  of  thickened  marginal  cells  forming  a  crest 
or  ridge.  Is  it  continuous  about  the  entire  capsule? 
Where  is  it  most  developed?  Is  the  capsule  more 
fragile  at  one  point  than  another?  Examine  several 
capsules  in  demonstrating  this  point.  Observe  the 
size,  shape  and  arrangement  of  the  lateral  or  parietal 
cells  of  the  capsule.  i 

(c)  The  Spores.— Rupture  sporangia  by  pressure  of  the 
cover  glass  and  examine  the  spores.  What  is  their 
color  and  shape? 

Make  drawings  which  illustrate  the  various  struc- 
tures studied  above. 

2.  The  Prothallium  (Gametophyte).— Study  prothallia  in 
their  normal  growing  condition  if  possible.  What  is  their 
general  appearance,  color  and  shape?  Carefully  isolate  a 
single  specimen  as  directed  by  the  instructor  and  proceed 
to  work  out  its  distinctive  morphological  features.  Is  it 
differentiated  into  an  upper  and  a  lower  surface?  If  so, 
what  are  the  distinguishing  characteristics?  Has  the  plant 
rootlike  organs  or  rhizoids?  \Vhere  are  they  located  and 
what  is  then-  probable  function? 

Carefully  examine  the  lower  surface  of  the  prothallium 
for  the  presence  of  the  following  organs: 

(a)  Antheridia.— These  are  small  somewhat  spherical 
bodies  usually  located  among  the  bases  of  the  rhizoids. 
They  correspond  to  the  male  sexual  organs  and  may 
contain  small  coiled  antherozoids,  the  male  sex  cells. 


THE  FERN  103 

(b)  Archegonia.  —  The  archegonia,  or  female  sex  organs, 
are  small,  finger-like  projections  in  the  region  of  the 
sinus,  or  notch,  of  the  prothallium.  Compare  care- 
fully their  shape  and  structure  with  that  of  the  an- 
theridia.  When  the  archegonia  are  mature  each 
one  contains  a  single  egg  cell. 

Make  drawings  showing  the  location  of  the  sex 

organs  on  the  prothallium,   and  also  showing  the 

character  of  these  organs  as  seen  with  higher  power. 

3.  Development.— After   fertilization,   which   takes    place 

within  the  archegonium,  the  fertilized  egg  cell  undergoes  a 

cleavage  and  gradually  develops  into  a  young  fern.    It  soon 

develops  its  own  roots  and  leaves  and  becomes  a  perfectly 

independent  plant.    The  plant  produced  in  this  way  is  the 

sporophyte  generation. 


YEAST. 

DISSOLVE  a  small  piece  of  compressed  yeast  in  water, 
mount  a  drop  on  a  slide  and  examine  with  the  compound 
microscope.  Or  better  mount  a  drop  of  Pasteur's  solution 
in  which  yeast  is  growing  vigorously. 

I.  Morphology. 

1.  Form.— What  is  the  form  of  the  yeast  cells?    Are  all 
cells  of  the  same  shape?    Are  they  single  or  in  groups? 
Are  the  cells  arranged  similarly  in  different  groups?    Are 
they  uniform  in  size?    Make  drawings  to  show  the  points 
observed. 

2.  Structure.— Is  a  cell  wall  present?    Note  its  color  and 
thickness.    Is  protoplasm  present  within  the  cell?     Does 
it  show  any  color?    Look  for  vacuoles  within  the  cell.    Is 
more  than  one  present?    Is  the  size  of  all  vacuoles  the  same? 
Is  there  any  difference  in  size  or  number  of  vacuoles  in  single 
cells  and  in  groups  of  cells?    Is  there  any  difference  in  size 
and  number  of  vacuoles  in  growing  yeast  and  yeast  from  a 
compressed  cake.    How  can  this  be  accounted  for?    Small 
glistening  oil  drops  are  often  present  near  the  vacuoles.    A 
nucleus  is  present  in  each  cell  but  it  can  be  demonstrated 
only  by  special  methods. 

H  Physiology. 

1.  Reproduction.— Examine  cells  from  actively  growing 
yeast  and  from  compressed  yeast  and  note  any  differences 


YEAST  105 

in  form,  number  and  size  of  cells  in  a  group.    Explain  the 
differences. 

The  chief  method  of  reproduction  in  yeast  is  by  asexual 
budding  or  gemmation.  How  does  this  method  differ  from 
fission  in  protozoa? 

2.  Growth.— In  the  following  experiments  the  amount 
and  rate  of  growth  may  be  roughly  estimated  by  the  in- 
crease in  the  turbidity  of  the  liquids;  fermentation  may  be 
indicated  by  the  rate  and  the  amount  of  gas  produced. 

(a)    Food  Supply    and    Growth.— Fill   four  test  tubes  (if 
fermentation  tubes  are  at  hand  better  results  will  be 
obtained  by  their  use)  half  full  of  the  following  fluids, 
and  into  each  place  the  same  amount  of  yeast  from 
the  same  culture.    Keep  all  the  tubes  under  the  same 
conditions. 
(I)  Distilled  water. 
II)  10  per  cent  sugar  solution. 

(III)  Pasteur's  solution  without  sugar. 

(IV)  Pasteur's  solution  with  sugar. 

After  several  hours  or  a  day  observe  the  tubes  and  deter- 
mine in  which  the  growth  and  fermentation  have  been  most 
rapid  and  greatest. 

(6)  Other  Conditions  and  Growth.— Prepare  several  tubes 
with  Pasteur's  solution  containing  sugar,  and  to  each 
add  the  same  amount  of  yeast.  Place  some  of  the 
tubes  in  a  warm  place  (about  35°  C) ;  some  in  a  cold 
place  (on  ice  if  possible) ;  boil  some  and  place  with 
the  first  ones;  to  some  add  a  few  drops  of  a  poison  like 
mercuric  chloride  or  formalin;  place  some  tubes  in 
the  sunlight  and  others  in  darkness.  Into  a  similar 
tube  place  some  yeast  filtrate.  After  several  hours, 
or  on  the  next  day  observe  the  tubes  and  note  all  the 
differences.  Draw  what  conclusions  you  can  as  to 


106  GENERAL  BIOLOGY 

the  effect  of  the  different  conditions  upon  the  growth 
of  yeast,  and  upon  its  power  to  cause  fermentation, 
(c)  Fermentation.— Conduct  some  of  the  gas  being  formed 
in  a  culture  of  vigorously  growing  yeast  through  lime- 
water  or  baryta-water.  What  is  the  effect  on  the 
lime-water?  A  milky  appearance  or  a  white  pre- 
cipitate indicates  the  presence  of  carbon  dioxide. 
Is  this  the  gas  which  is  being  produced  by  the  yeast? 
Permit  yeast  to  grow  in  a  large  flask  of  Pasteur's 
solution  until  growth  has  ceased,  i.  e.,  until  gas  is  no 
longer  evolved.  Distill  the  contents  of  the  flask  at 
a  low  temperature  (about  80°  C)  and  test  the  dis- 
tillate for  alcohol  by  odor,  taste,  and  inflammability. 
(The  test  will  be  more  certain  if  a  second  distilla- 
tion is  made.)  What  conclusions  can  you  draw  from 
the  experiment? 

From  the  experiments  upon  the  life  and  activities  of 
yeast  write  a  report  clearly  showing  the  nature  of  the  experi- 
ments, the  results,  and  the  conclusions  which  may  logically 
be  drawn  from  them.  Give  a  summary  of  the  conditions 
which  are  favorable  and  those  which  are  unfavorable  for 
growth  and  ferment  action  of  yeast. 


BACTERIA. 

BACTERIA  flourish  only  in  the  presence  of  moisture,  but 
are  found  in  soil  and  air;  indeed  hardly  any  condition  where 
life  is  possible  is  devoid  of  bacteria.  Some  are  among  the 
most  useful  and  important  of  organisms,  and  others  are 
among  the  most  dreaded  and  dangerous  of  all  living  things. 
Many  of  the  most  virulent  of  diseases  which  afflict  mankind 
have  been  traced  directly  to  bacteria.  Some  study  of  their 
peculiarities,  conditions  of  activity,  method  of  protection 
from  them  may  be  of  interest  and  importance  economically 
and  biologically. 

I.  Morphology. 

Mount  a  drop  of  water  from  a  hay  or  other  infusion  of 
organic  matter,  or  from  slime  in  aquaria,  and  examine  under 
the  highest  power  of  the  microscope.  Note  the  numbers  of 
very  minute,  almost  transparent  bodies  present,  some  in 
motion  and  others  quiescent. 

The  forms  of  bacteria  are  very  simple  and  comprise  only 
three  principal  types:  the  sphere-  (coccus),  the  rod  (bacillus), 
and  the  spiral  (spirillum).  How  many  of  these  kinds  are 
distinguishable  in  your  preparation?  Is  the  size  variable? 
Which  type  is  generally  largest,  and  which  smallest?  Is 
the  movement  which  is  taking  place  a  locomotion  or  merely 
a  vibration  or  oscillation? 

Make  drawings  to  show  the  shape  and  relative  size  of  the 
types  of  bacteria  found. 


108  GENERAL  BIOLOGY 

II.  Reproduction. 

Bacteria  reproduce  chiefly  by  fission,  hence  the  scientific 
name  of  the  order,  Schizomycetes  (Fission  fungi).  One 
indication  of  this  fission  which  may  easily  be  observed  is 
the  presence  of  chains  or  groups  of  bacteria.  In  what  way 
is  this  an  evidence  of  division? 

HI.  Physiology. 

Bacteria  are  plants  but  are  not  able  to  manufacture  their 
food  as  the  green  plants  do.  In  order  to  grow  they  must 
be  in  a  medium  which  contains  available  food,  and  the 
culture  media  used  for  their  growth  are  so  prepared  as 
to  furnish  the  conditions  necessary  for  their  growth  and 
activity. 

1.  Distribution  of  Bacteria.— Methods  of  preparing  the 
nutritive  media  can  be  found  in  any  of  the  manuals  on  bacter- 
iology. With  tubes  or  Petri  dishes  containing  sterilized 
gelatin  make  the  following  experiments : 

(a)    Keep  some  carefully  closed  and  labeled  "not  exposed." 

(6)  Expose  some  to  the  air  of  the  laboratory  for  three 
minutes,  and  label  accordingly. 

(c)  Expose  some  to  the  dust  from  laboratory  tables  or 
floor,  or  dust  from  the  outside. 

(d)  Let  a  drop  of  water  from  the  laboratory  tap  flow  over 
another. 

0)    Capture  a  fly  and  let  it  walk  over  the  gelatin. 

Set  these  aside  in  a  warm  place  and  examine  after  a  day 
or  two,  noting  what  differences  there  are  in  the  several 
dishes.  The  small  spots  or  patches  probably  present  are 
colonies  of  bacteria.  Do  they  differ  in  form  and  color? 
Examine  the  series  still  later.  Have  the  colonies  grown? 


BACTERIA  109 

How  is  this  indicated?  Do  any  of  the  colonies  have  any 
effect  on  the  gelatin? 

2.  Surrounding  Conditions  and  Growth.— Into  tubes  of 
bouillon  introduce  several  drops  of  fluid  from  some  culture 
of  bacteria  and  treat  the  tubes  as  follows : 

(a)    Close  the  tube  with  a  plug  of  cotton. 

(6)    Close  the  tube  with  cotton  and  boil  for  five  minutes. 

(c)  To  a  third  tube  add  a  small  portion  of  a  poisonous 
substance,  such  as  corrosive  sublimate  or  formalin. 

(d)  Place  some  tubes  in  the  bright  sun  and  others  in  the 
dark;   place  some  on  ice  and  others  in  a  warm  place. 

Label  all  the  tubes  and  set  away  for  a  day  or  more.  Ob- 
serve and  note  changes,  if  any,  as  indicated  by  the  odor 
and  cloudy  appearance  of  the  culture  fluid.  Explain  the 
differences. 


THE  CRAYFISH. 

CAMBARUS  SP. 

I.  External  Anatomy. 

COMPARE  with  the  earthworm  with  regard  to  regional 
differences  such  as  anterior  and  posterior  ends,  dorsal  and 
ventral  sides,  head  and  tail.  Are  these  regions  more  or  less 
sharply  marked?  Is  there  perfect  bilateral  symmetry? 

Distinguish  an  anterior  region,  the  cephalothorax,  and  a 
posterior,  the  abdomen.  In  what  ways  are  they  alike? 
In  what  different?  Is  there  a  definite  head?  Note  the 
exoskeleton,  is  it  present  everywhere?  Where  is  it  thickest 
and  hardest,  where  thinnest?  What  explanation  can  you 
give  for  these  differences? 

1.  Abdomen.— Is  it  segmented?    If  so,  how  many  seg- 
ments?   The  last  segment  is  called  the  telson.     Does  it 
differ  from  other  segments?    Is  free  movement  of  the  seg- 
ments possible?    Is  it  equal  in  all  directions?    How  are 
the  segments  joined  together?    Are  appendages  present? 
Are  they  present  on  all  segments  ?    Are  they  alike  ? 

2.  Cephalothorax.— Is  the  form  like  that  of  the  abdomen? 
Are  segments  present?     Is  there  any  thing  to  suggest  seg- 
mentation?   The   shell-like  exoskeleton   in   this  region   is 
called  the  carapace.    Are  the  edges  of  the  carapace  free  or 
fixed?    To  what  extent?    Are  the  appendages  of  this  region 
similar  in  form? 

3.  Sexes.— Distinguish  the  following  characters: 


THE  CRAYFISH  111 

(a)  Male.— The  first  abdominal  appendages  are  modified 
into  tube-like  or  spine-like  organs;  the  abdomen  is  narrower 
than  the  thorax;  the  genital  openings  are  on  the  bases  of 
the  hindmost  legs. 

(6)  Female.— The  abdomen  is  slightly  broader  than  the 
cephalothorax;  the  genital  ducts  open  on  the  bases  of  the 
third  pair  of  legs.  What  is  the  character  of  the  first  abdom- 
inal appendages? 

4.  External  Openings.— (a)  auditory,  on  the  dorsal  side 
of  the  basal  joint  of  the  antennules;  ('&)  excretory,  at  the 
base  of  the  antennae  on  the  ventral  side;  (c)  mouth,  on  the 
ventral  side  between  the  jaws;  (d)  genital  ducts  already 
noted;  (e)  anus,  on  the  ventral  side  of  the  last  segment  of 
the  body. 

Draw  the  entire  animal  from  the  side,  X  2. 

II.  Appendages. 

1.  Abdominal.— Carefully    dissect    the    appendages    from 
one  side  of  the  abdomen  and  arrange  them  in  order  on  a 
piece  of  paper.    Using  the  third  appendage  as  a  type  notice 
its  biramous  character ;    there  is  a  basal  portion,  the  pro- 
topodite,   and  two  distal  portions,  the   exopodite  and  the 
endopodite.     Compare  the  other  appendages  with  this  one 
and  determine  whether  they  have  the  same  structure.    Are 
there  any  variations  from  this  structure?    What  are  they? 
Which    appendages   show   the    greatest   modification?    In 
what  way?    Can  you  explain  it?     Draw  the  first,  the  third 
and  the  last  appendage. 

2.  Cephalothoracic.— In  a  similar  manner  dissect  off  the 
walking  appendages  from  the  same  side  of  the  animal  and 
arrange  them  in  order  as  before.     Explain  such  differences 
in  structure  as  appear.    Do  these  appendages  bear  any 


112  GENERAL  BIOLOGY 

resemblance  to  the  third  abdominal?  Are  protopodite, 
exopodite  and  endopodite  present? 

Draw  the  first,  the  third  and  the  last  walking  appendages. 
The  first  pair  are  called  chelae. 

Remove  the  mouth  parts  on  the  same  side,  and  arrange 
them  in  order.  From  the  outside  inward  they  are  called: 
3d  pair  of  maxillipeds,  2d  pair  of  maxillipeds,  1st  pair  of 
maxillipeds,  2d  pair  of  maxillae,  1st  pair  of  maxillae,  mandibles. 
Compare  each  one  of  these  with  the  third  abdominal  ap- 
pendage and  with  the  walking  appendages.  Are  they  bira- 
mous,  are  the  protopodite,  the  exopodite,  and  the  endopodite 
present?  Are  the  appendages  of  this  group  alike?  Might 
they  be  considered  as  modifications  of  a  common  structure? 
Do  they  have  the  same  number  of  joints  as  the  walking 
appendages?  In  the  2d  maxilla  note  the  gill  bailer  which 
lies  in  the  gill  chamber  and  whose  movement  creates  a 
current  of  water  which  passes  over  the  gills. 

Draw  the  3d  maxilliped,  the  2d  maxilla,  and  the  mandible. 

Remove  the  antenna  and  the  antennule  from  the  same 
side  of  the  body.  Compare  with  the  other  appendages, 
what  are  the  likenesses  and  the  differences?  Draw. 

Considering  all  the  appendages,  indicate  whether  there 
is  a  common  plan  in  their  structure,  and  if  so  what  it  is. 
Also  indicate  what  the  departures  from  this  plan  have  been, 
and  suggest  advantages  of  these  variations.  Parts  having 
the  same  fundamental  structure  are  said  to  be  homologous; 
and  in  this  animal  there  is  represented  a  serial  homology. 

HE.  Internal  Anatomy. 

1.  Respiratory  System.— Carefully  cut  away  the  carapace 
from  the  side  of  the  body  and  expose  the  gill  chamber  and 
the  gills  contained  therein.  What  is  the  form  of  the  gills? 


THE  CRAYFISH  113 

Of  what  advantage  is  this  form?  To  what  are  the  gills 
fastened?  How  does  the  water  get  to  the  gills?  Why  are 
they  under  the  carapace? 

2.  Circulatory    System.— Carefully    remove    the    carapace 
from  the  dorsal  side  of  the  body.    The  heart  will  be  found 
in  the  posterior  portion  of  the  cephalothorax,  as  a  delicate 
shield-shaped  body.    Notice  any  vessels  which  extend  out 
from  the  heart  and  examine  an  injected  specimen,  if  one  is 
available.     Note  the  small  openings  in  the  heart,  these  are 
valves.     In  what  direction  do  they  permit  the  blood  to  flow? 
Trace  all  the  bloodvessels  which  can  be  found. 

3.  Reproductive  System.— The  ovaries  are  granular  bodies 
of  considerable  size  located  in  the  dorsal  part  of  the  thorax 
and  abdomen.     Note  the  shape  and  extent  of  the  organ 
and  trace  the  ducts  to  the  openings  already  noted.    The 
testes  are  in  a  similar  position  but  are  smaller  and  are  of  a 
whitish  color;    the  sperm  ducts  are  somewhat  coiled  and 
longer  than  the  oviducts. 

4.  Digestive  System.— Remove  the  gills  from  one  side  of 
the  body  and  cut  away  the  body  wall  of  the  same  side.    This 
will  expose  the  greenish  liver  and  the  other  digestive  organs. 
Remove  .the  lobe  of  liver  on  this  side  and  expose  the  stomach 
and  intestine. 

In  the  extreme  anterior  part  of  the  body  cavity  will  be 
found  the  large  stomach  composed  of  two  parts,  from  which 
the  intestine  leads  backward  to  the  anus.  Between  the 
mouth  and  the  stomach  there  is  a  short  esophagus.  Trace 
the  digestive  tube  from  the  mouth  to  the  anus,  observing 
the  shape  and  the  size  of  the  parts  and  their  exact  position. 
Do  the  large  digestive  glands,  or  livers,  open  into  the  intestine 
or  the  stomach? 

Draw  the  animal  from  the  side  as  opened  and  show  all 
the  organs  that  are  exposed  or  that  can  be  seen  by  dissection. 
8 


114  GENERAL  BIOLOGY 

Open  the  stomach  and  observe  the  character  of  the  lining. 
Of  what  use  are  the  teeth  that  are  present  in  the  walls  ?  How 
do  they  operate?  If  food  is  present  in  the  stomach  try  to 
determine  its  character. 

5.  Excretory    System.— The    openings    have    been   noted 
as  being  on  the  basal  joint  of  the  antenna?.    The  excretory 
organs  themselves,  the  kidneys  or  green  glands,   lie  just 
dorsal  to  the  bases  of  these  antenna?  and  therefore  in  the 
extreme  anterior  part  of  the  body  cavity. 

6.  Nervous  System.— Dissect  the  muscle  and  other  tissues 
from  the  abdomen  and  expose  the  nerve  cord.     Be  careful 
not  to  break  any  of  the  nerves  in  cleaning  away  the  muscle. 
Expose  the  cord  to  the  extreme  posterior  part  of  the  abdo- 
men, then  trace  it  forward  into  the  thorax,  dissecting  as 
much  as  is  necessary  to  expose  it.    In  the  anterior  part  of 
the  body  the  cord  will  be  found  to  divide  into  two  parts, 
forming  a  commissure  which  passes  around  the  esophagus 
to  the  dorsal  side.    Here  the  two  cords  unite  again  to  form 
the  cerebral  ganglia  or  brain. 

Notice  the  number,  position,  arrangement  of  the  ganglia, 
then*  size,  the  distribution  of  the  nerves  which  come  from 
them,  and  the  termination  of  the  nerves  of  the  brain  in  the 
sense  organs  of  the  head.  Compare  this  nervous  system 
with  that  of  the  earthworm. 

Make  an  enlarged  drawing  of  the  entire  system. 

IV.  Physiology. 

1.  Locomotion.— In  working  on  the  living  animals  do 
not  excite  or  irritate  them.  Place  the  crayfish  in  a  pan 
with  sufficient  water  to  cover  it  and  observe  it  while  walk- 
ing_or  crawling.  What  appendages  are  used?  Can  it  walk 
backward  as  well  as  forward?  Are  the  legs  used  in  any 


THE  CRAYFISH  115 

definite  order?  Place  the  animal  on  the  table,  does  it 
walk  equally  well  out  of  water?  While  the  animal  is  in  the 
water  frighten  it  by  thrusting  a  pencil  at  it;  notice  how  it 
swims,  what  parts  are  used  and  how?  What  advantage 
comes  from  swimming  in  this  direction? 

2.  Defense.— With  a  pencil  make  motions  at  an  animal 
to  see  how  it  defends  itself.    Allow  it  to  grasp  the  pencil 
to  show  the  strength  of  the  grasp. 

3.  Respiration.— While  the  animal  is  at  rest  in  the  water 
place  a  little  colored  liquid  near  the  bases  of  the  legs.    Where 
is  this  liquid  drawn  into  the  animal  and  where  does  it  re- 
appear?   Try  dropping  the  colored  liquid  at  various  places 
along  the  edge  of  the  carapace.    What  causes  the  movement 
of  the  liquid?    What  purpose  do  the  currents  serve?     How 
is  it  that  a  crayfish,  while  breathing  by  gills,  can  live  for 
some  time  out  of  water? 

4.  Sensitiveness.— Note  the  range  of  motion  of  the  eyes. 
Could  an  enemy  approach  the  animal  from  any  direction 
without  being  seen?    What  are  the  advantages  and  what 
the  disadvantages  of  having  the  eyes  on  movable  stalks? 
In  what  ways  are  the  eyes  protected?    Touch  one  of  the 
eyes  and  see  what  happens. 

Test  the  sense  of  touch  at  various  places  on  the  body; 
where  is  it  most  sensitive?  Are  all  parts  of  the  appendages 
equally  sensitive?  Touch  some  of  the  hairs  at  different 
places  on  the  body;  are  they  sensitive? 

5.  Feeding.— Small  pieces  of  meat  may  be  placed  near 
the  animal  to  determine  how  it  reacts,  and  also  to  show  in 
what  way  the  food  is  grasped  and  how  it  is  passed  to  the 
mouth.    If  possible  note  the  action  of  the  different  mouth 
parts.    If  this  sort  of  a  test  is  made  you  should  also  deter- 
mine whether  the  animal  prefers  fresh  or  decaying  meat. 


THE  GRASSHOPPER. 

THE  following  outline  will  apply  to  any  of  the  common 
grasshoppers,  though  the  larger  ones  are,  of  course,  pref- 
erable for  the  study  of  the  structure. 

I.  External  Anatomy. 

1.  General  Characters.— The  body  of  the  grasshopper  is 
made  up  of  head,  thorax  and  abdomen.     Are  these  divisions 
well  marked  ?    Are  they  as  well  differentiated  as  in  the  crayfish 
and  earthworm?    Are  somites  present  ?    Are  they  found  in  all 
regions  of  the  body?    Is  an  exoskeleton  present?     Compare 
with  the  crayfish  in  regard  to  exoskeleton.    In  what  ways 
do  they  differ?    Are  appendages  present?    Are  they  found 
in  all  regions  of  the  body? 

2.  The  Head.— What  is  its  shape?    How  is  it  attached 
to  the  thorax?     Study  the  position  and  structure  of  the 
antennae.     Observe  the  large  compound  eyes.     With  a  lens 
determine  why  these  are  called  compound  eyes.     In  addition 
to  these  eyes  there  are  three  simple  eyes  or  ocelli.     One  in 
the  center  of  the  head,  below  the  antenna?,  and  the  others 
near  the  dorsal,  anterior  border  of  the  compound  eyes. 

About  the  mouth  are  several  appendages:  (a)  labrum, 
or  upper  lip;  (6)  mandibles,  or  jaws;  (c)  maxillae;  (rf) 
labium  or  lower  lip.  Observe  the  position  each  occupies 
and  the  direction  of  movement.  Remove  the  appendages, 
note  the  structure  of  each  one  and  make  a  drawing  showing 
this  structure. 


THE  GRASSHOPPER  117 

3.  Thorax.— Distinguish    the    Following    divisions:      (a) 
prothorax,  (6)  mesothorax,  (c )  metathorax.     These  three  parts 
of  the  thorax  represent  somites.     Are  they  sharply  separated 
from  each  other?     Do  they  move?    In  what  respects  do 
they  correspond  to  typical  segments  of  the  crayfish?    Ob- 
serve the  several  plates  of  which  each  is  composed.    What 
appendages  are  borne  by  each  somite? 

4.  Appendages   of   the    Thorax.  — (a)    Legs.     How   many? 
Distinguish  the  following  joints:     coxa,   a  short  segment 
next  to  the  body;    trochanter,  the  second  segment,  which 
may  be  fused  with  the  first  in  the  jumping  legs;    femur, 
the  middle  segment;    tibia;    tarsus  or  foot.    Is  the  tarsus 
a  single  piece?    Compare  the  several  parts  of  each  of  the 
legs  with  corresponding  portions  of  the  others.    In  what 
are  they  alike  ?     In  what  different  ? 

(6)  Wings.— How  many?  On  which  somites  are  they 
borne?  Note  their  size,  color,  and  texture.  What  is  their 
relative  position  in  repose?  In  flight?  Spread  the  wings 
and  study  the  arrangement  of  the  veins. 

Make  drawings  of  the  first  and  third  legs,  and  of  both  pairs 
of  wings.  • 

5.  Abdomen.— Of   how    many    somites   is    it   composed? 
Compare  the  male  and  female  specimens  carefully  in  shape, 
size,  number  and  relations  of  the  somites.    In  what  partic- 
ulars do  they  differ?    Compare  the  first  somite  with  those 
following  and  note  any  differences.    In  this  somite  there 
is  a  membranous  tympanum  or  ear  drum. 

Study  the  structure  of  a  somite  and  observe  a  dorsal 
portion,  the  tergum  and  a  ventral  sternum.  Are  these  parts 
well  marked?  Are  they  present  in  each  somite?  Are  the 
terga  and  sterna  capable  of  movement? 

In  the  side  walls  of  the  somites  are  small  openings  or 
pores  called  spiracles.  These  are  the  external  openings  of 


118  GENERAL  BIOLOGY 

the  respiratory  system,  which  is  made  up  of  a  series  of 
branching  tubes  inside  the  body  for  carrying  air  to  the 
various  organs  and  tissues.  There  are  eight  pah's  of  spiracles 
in  the  abdomen,  and  two  in  the  thorax;  determine  the 
exact  location  of  these. 

At  the  end  of  the  abdomen  the  somites  are  considerably 
modified,  to  form  spines,  plates  and  the  like.  The  hard 
spines  in  the  female  comprise  the  ovipositor,  or  egg-laying 
organ.  Determine  the  number  of  spines  and  the  relation 
of  these  to  the  somites  adjoining.  In  the  male  there  are 
smaller  spines  which  function  as  genital  organs  during  mating. 
In  both  males  and  females  the  anal  opening  is  dorsal, 
beneath  a  chitinous  plate,  and  the  reproductive  opening 
is  toward  the  ventral  side. 

Make  a  drawing  of  the  entire  animal  from  the  side. 


II.  Internal  Anatomy. 

Remove  the  wings  and  cut  along  each  side  of  the  median 
dorsal  line.  Remove  the  entire  dorsal  part  of  the  body 
wall  and  expose  the  internal  organs. 

1.  Respiratory   System.— Tracheae  or  air-tubes  will  be  seen 
as  fine  white  tubes,  much  branched  and  extending  to  all 
organs  and  tissues  of  the  body.    The  tracheae  open  to  the 
outside  through  the  spiracles.    Demonstrate  this  connection. 

2.  Digestive    System.— Distinguish    the    following   parts: 
(a)  esophagus,  leading  from  the  mouth  to  the  crop;    (6) 
crop,  a  large  organ  located  in  the  prothorax;    (c)  gastric 
caeca,  a  series  of  pouches  surrounding  the  posterior  end  of 
the  crop;    how  many  are  there?    Do  they  connect  with 
the  cavity  of  the  crop?     (d)  The  stomach  is  an  enlarged 
part  behind  the  cseca;    (e)  intestine  the  posterior  portion 


THE  GRASSHOPPER  119 

of  the  digestive  tube  ending  at  the  anus.    The  intestine  is 
made  up  of  three  parts. 

3.  Excretory  System.— This  comprises  a  number  of  deli- 
cate  capillary    tubes,   the   Malpighian    tubules,   which  are 
twisted  together  and  may  partly  fill  the  body  cavity.    They 
connect  with  the  digestive  canal  at  the  point  where  the 
stomach  and  intestine  join. 

4.  Reproductive  System.— The  reproductive  organs,  testes 
or  ovaries,  are  present  in  the  abdomen,  dorsal  to  the  digestive 
tube.    These  organs  are  made  up  of  tubules  closely  packed 
together.    They  open  to  the  exterior  through  the  sperm 
ducts  or  oviducts,  whose  openings  are  ventral  to  the  anal 
opening.    The  ovary  in  mature  animals  may  be  a  mass  of 
eggs  completely  filling  the  body  cavity. 

Make  a  large  drawing  to  show  all  the  organs  and  systems 
worked  out. 

5.  Nervous  System.— Remove  the  alimentary  canal  and 
the  reproductive  organs.    The  nerve  cord  should  now  appear 
along  the  median  ventral  line,  covered  over   with  a  thin 
sheet  of  fat   tissue.     Are   ganglia    present?     How    many 
in  the  abdomen?     In  the  thorax?    Is  there  a  ganglion  to 
each  somite?    Where  are  the  ganglia  largest?    Trace  the 
general  direction  of  the  nerves  which  leave  the  ganglia. 
In  the  head  is  a  ventral  inf ra-esophageal  ganglion,  and  a  dorsal 
supra-esophageal  ganglion  or  brain.    These  two  large  ganglia 
are  connected  by  circum-esophageal  commissures.     From  the 
brain  nerves  go  to  the  ocelli,  compound  eyes,  and  antennae. 

Make  a  large  drawing  showing  the  nervous  system. 

Compare  the  crayfish,  the  grasshopper  and  the  earth- 
worm in  regard  to:  (a)  The  plan  upon  which  the  body  is 
constructed;  (6)  the  organization  of  somites  into  well 
defined  regions;  (c)  the  arrangement  and  structure  of  the 
appendages;  (d)  the  number,  position  and  structure  of 


120  GENERAL  BIOLOGY 

the  sense  organs;  (e)  the  structure  of  the  circulatory, 
digestive  and  nervous  systems.  Which  of  these  animals  is 
the  more  highly  specialized?  Is  one  better  adapted  to  its 
modes  of  life  than  the  others?  Give  reasons  for  your  con- 
clusions. 

m.  Physiology. 

From  a  study  in  the  field  and  in  the  laboratory  work  out 
the  following  activities  of  the  grasshopper. 

1.  Movements.— Describe    the    kinds    and    methods    of 
locomotion.    What    structural    features    of    the    legs    are 
adaptations  for  leaping?     How  many  times  the  length  of 
the  body  may  the  grasshopper  leap?     What  is  the  purpose 
of  the  hooks  on  the  legs?    Are  both  pairs  of  wings  used  for 
flight? 

2.  Sensitiveness.— With  a  bristle  touch  various  parts  of 
the  body,  including  the  antennae .     Which  is  the  most  sensitive 
part?     Does  the  grasshopper  see?     What  evidence  is  there 
of  this?    Is  there  any  evidence  that  it  hears? 

3.  Protection.— Has  the  grasshopper  any  means  of  de- 
fense?   Is  it  protected  by  color?     How  does  it  escape  its 
enemies? 

4.  Respiration.— Observe   the   respiratory   movements   of 
the  abdomen.     Knowing  the  structure  of  the  respiratory 
system,  which  is  characteristic  of  all  insects,  explain  why 
non-poisonous  powders  may  often  kill  insects. 

5.  Nutrition. — Place  animals  in  a  cage  with  leaves  of  grass 
and  other  plants.     If  possible  observe  the  method  of  using 
the  different   mouth  parts.    By  using  different  kinds   of 
plants  it  may  be  possible  to  determine  whether  there  is  any 
choice  of  food. 


HONEY  BEE. 

APIS  MELLIFICA. 

THE  honey  bee  belongs  to  the  class  Insecta  and,  there- 
fore, has  certain  characteristics  in  common  with  the  grass- 
hopper and  other  insects.  For  example,  there  is  the  same 
division  into  head,  thorax  and  abdomen;  a  subdivision  of 
thorax  and  abdomen  into  segments;  and  a  similar  number 
and  disposition  of  antennae,  eyes,  legs  and  wings.  The 
grasshopper,  however,  is  a  relatively  simple  insect,  wThile 
the  bee  is  one  of  the  most  complex.  The  bee  is  of  interest 
from  its  habit  of  community  or  social  life,  with  different 
castes  or  classes  in  the  community.  It  is  also  of  interest 
in  its  highly  specialized  and  adapted  organs,  as  compared 
with  the  more  simple  ones  of  the  grasshopper. 

External  Anatomy. 

1.  General  Characters.— Notice  the  division  of  the  body 
into  regions,  and  compare  with  the  grasshopper.    Especially 
note  the  covering  of  hairs  over  the  body,  is  this  present  in 
all  parts  or  is  it  limited  in  distribution?     Remove  some 
of  the  hairs,  place  on  a  slide  and  examine  with  the  com- 
pound  microscope.    The  longer  hairs  of  the  body  differ 
in  what  way  from  the  shorter  hairs  of  the  appendages? 

2.  Head.— Is  the  head  freely  movable?     Is  it  more  or 
less  so  than  in  the  grasshopper?    The  compound  eyes  are 
quite  similar  to  those  of  the  grasshopper,  but  observe  the 
short  spine-like  hairs  on  their  surface.     Compare  the  com- 


122  GENERAL  BIOLOGY 

pound  eyes  of  a  worker  and  of  a  drone  bee;  in  what  respects 
do  they  differ?  What  explanation  can  you  give  for  this 
difference?  The  eyes  of  the  queen  are  like  those  of  the 
workers.  Three  ocelli  are  present  as  in  the  grasshopper. 
Observe  the  position  and  the  structure  of  the  antennae. 

3.  Mouth  Parts.— The  mouth  parts  of  the  bee  are  the  same 
in  number  as  those  of  the  grasshopper,  but  greatly  modified 
and  adapted  to  different  functions. 

(a)  Labrum.— This  is  a  flap  of  skin  forming  an  upper  lip. 
(6)  Mandible.— There  is  a  pair  of  mandibles  or  jaws  be- 
hind the  labrum.  Both  the  mandible  and  the  labrum 
are  quite  similar  to  those  of  the  grasshopper,  but 
somewhat  reduced  in  size.  The  mandibles  of  the 
worker  differ  slightly  from  those  of  the  queen  and  the 
drone. 

The  remaining  mouth  parts,  the  maxillae  and  labium, 
are  much  modified  and  together  form  a  proboscis  for 
sucking  liquid  food. 

(c)  Maxilla.— The  palp  of  the  maxilla  is  reduced  in  size  to 

a  mere  rudiment.  The  remainder  of  the  appendage 
forms  the  hollow  outer  portion  of  the  proboscis. 

(d)  Labium.— Of  this  appendage   there   are  three   chief 

parts,  the  base,  the  labial  palps,  and  the  glossa  or 
"  tongue.  "  The  glossa  forms  the  center  of  the  pro- 
boscis, is  covered  with  long  hairs,  and  ends  in  a  spoon- 
like  lobe  called  the  labellum. 

To  study  the  mouth  parts  straighten  them  out, 
away  from  the  head,  cut  off  the  entire  tip  of  the  head 
and  mount  this  on  a  slide  in  glycerin.  It  may  be 
necessary  to  separate  these  parts  somewhat  with 
needles. 
Make  a  drawing  of  the  mouth  parts. 


HONEY  BEE  123 

4.  Thoracic  Appendages.  —  (a)  Wings. — Remove  the  wings 
from  the  body  and  mount  on  a  slide.  Study  the 
arrangement  of  the  veins  in  each  wing.  With  the 
compound  microscope  observe  the  hooks  on  the  an- 
terior border  of  the  hind  wings  which  attach  this  to 
the  fore  wing.  What  is  there  on  the  fore  wing  to  hold 
these  hooks? 
Make  a  drawing  of  the  wings. 

(6)  Legs.— The  legs  are  composed  of  five  segments  as 
those  of  the  grasshopper,  but  the  basal  joint  of  the 
tarsus  or  foot  is  much  enlarged  and  is  sometimes 
called  the  metatarsus.  The  legs  of  the  bee  serve  not 
only  for  locomotion,  but  also  as  tools  for  other  com- 
plex functions. 

1.  Prothoracic  Leg.— Between  the  tibia  and  the  first 
tarsal  segment  is  the  antenna  cleaner;  on  the  outer 
end  of  the  tibia  is  a  pollen  brush,  composed  of  stiff 
hairs. 

2.  Mesothoracic  Leg.— At  the  end  of  the  tibia  is  a  long 
spine,  the  pollen  spur. 

3.  Metathoracic  Leg.— How  do  the  tibia  and  first  tarsal 
joint  compare  in  size  with  similar  parts  of  the  other 
legs?    The  outer  surface  of  the  tibia  is  hollowed 
out  to  form  the  pollen  basket;  the  inner  surface  of 
the  first  tarsal  joint  is  covered  with  rows  of  stiff 
spines,  the  pollen  combs.    Between  the  tibia  and 
the  first  tarsal  joint  are  the  so-called  wax  shears, 
which,  however,  are  used  in  gathering  pollen  and 
have  nothing  to  do  with  wax  manipulation. 

Compare  these  adaptive  specializations  of  the  legs  of  the 
worker  with  the  legs  of  the  drone,  and  note  what  differences 
occur.  Is  it  possible  to  explain  these  differences? 

Remove  each  of  the  legs  from  the  body,  study  with  a 


124  GENERAL  BIOLOGY 

lens  or  low  power,  and  make  drawings  to  show  the  points 
observed. 

5.  The  Sting.— The  sting  is  located  in  a  cavity  in  the  end 
of  the  abdomen,  which  is  formed  by  an  infolding  of  some 
of  the  posterior  abdominal  segments.  The  sting  is  homol- 
ogous with  the  ovipositor  of  other  insects. 

Remove  the  dorsal  wall  of  the  end  of  the  abdomen  and 
dissect  out  the  sting  apparatus.  Mount  this  on  a  slide  in 
glycerin  and  study  with  low  power.  There  is  a  shaft  com- 
posed of  a  dorsal  sheath  and  two  barbed  lancets  or  darts. 
The  sheath  and  lancets  form  a  hollow  tube  through  which 
the  poison  flows.  At  the  sides  is  a  pair  of  sting  palps,  soft 
whitish  projections,  which  serve  as  sense  organs  by  which 
the  bee  can  tell  when  she  is  in  contact  with  the  object  which 
is  to  be  stung.  When  the  sting  apparatus  is  removed  one 
or  both  of  the  poison  glands  will  usually  be  present.  Other 
parts  of  the  complicated  apparatus  will  also  be  found. 
Determine  the  character  of  the  sting  proper  and  the  palps, 
and  make  a  drawing  to  show  the  structures  observed. 

As  a  portion  of  this  study  the  different  classes  of  the  com- 
munity, drones  (males),  queens  (females),  and  workers 
(neuters  or  imperfect  females),  should  be  compared.  Es- 
pecially should  this  comparison  be  made  to  determine  the 
differences  in  structure  which  are  correlated  with  the  speciali- 
zations of  parts  for  particular  functions. 

Field  studies  should  be  made,  if  possible,  to  observe  the 
habits  of  the  bees,  especially  that  of  gathering  nectar  and 
pollen.  An  interesting  study  of  the  activities  within  the 
hive  can  be  made  if  an  observation  hive  of  glass  is  available. 


THE  CLAM. 

UNIO  SP. 

THE  common  fresh-water  mussels  or  clams,  of  almost  any 
genus,  are  excellent  for  study.  Those  of  some  size  are  best. 
The  marine  clam  (Venus)  while  not  so  large  nor  so  satis- 
factory, is  quite  similar  in  most  of  its  structural  features. 
Clams  live  partly  buried  in  the  sand  or  mud,  writh  the  pos- 
terior end  of  the  body  protruding.  They  may  be  collected 
by  digging.  It  is  possible  to  keep  them  alive  for  some  time 
if  placed  in  tanks  of  running  water. 

I.  External  Anatomy. 

1.  Shell.— Note  the  general  form  and  relations  of  the  shell. 
Are  the  valves  (the  two  parts  of  the  shell)  similar  in  size  and 
form?  The  dense  horny  hinge  is  the  dorsal  part,  and  the 
knob  or  elevation  on  the  shell  (umbo)  is  nearer  the  anterior 
end.  Has  the  animal  a  right  and  a  left  side?  Observe  the 
parallel,  concentric  lines  extending  from  the  umboes  to  the 
margins  of  the  valves;  they  indicate  lines  of  growth,  though 
their  number  gives  no  evidence  of  the  age  of  the  clam. 
Each  line  wras  at  one  time  the  edge  of  the  shell.  Study 
the  action  of  the  ligament  or  hinge  in  a  recently  opened  shell ; 
what  function  does  it  serve?  The  ligament  is  an  uncal- 
cified  portion  of  the  shell. 

Make  a  drawing  of  the  shell  from  the  side,  and  one  from 
the  anterior  aspect. 


126  GENERAL  BIOLOGY 

2.  Interior  Surface  of  the  Shell.— Wedge  the  shell  open 
and  then  cut  the  muscles  which  are  attached  to  the  valves. 
When  this  is  done  what  happens  to  the  valves?  What 
causes  this?  What  is  the  function  of  the  muscles?  (If  the 
animal  is  preserved  and  the  valves  are  already  open,  cut 
the  muscles  and  determine  the  functions  of  muscle  and 
ligament.)  Cut  the  ligament  and  remove  the  left  valve, 
being  careful  not  to  remove  any  of  the  body  within  the 
shell;  a  fold  of  skin  which  sticks  to  the  shell  must  be  care- 
fully separated. 

Compare  the  color  and  markings  of  the  interior  of  the 
shell  with  those  on  the  outside.  Are  lines  of  growth  present? 
Are  there  any  scars  on  the  inside  of  the  shell?  What  has 
been  the  cause  of  these?  Find  the  marks  made  by  the 
adductor,  retractor,  and  protractor  muscles.  (In  Venus  there 
is  no  protractor  muscle.)  How  many  of  these  muscles  are 
there?  What  is  their  function?  When  the  clam  was 
smaller  than  it  is  now  where  were  the  muscles  attached? 
How  do  you  know?  Is  there  any  evidence  of  growth  over 
any  part  of  the  muscle  scars  that  now  show?  At  the  dorsal 
side  of  the  valve  notice  several  teeth  (not  present  in  all 
clams),  the  hinge  teeth.  WTiat  is  their  function? 

Draw  the  interior  of  the  shell. 

3.  Structure  of  the  Shell.—  Break  the  valve  that  has  been 
removed  and  examine  the  broken  surface.  Notice  the 
thickness  of  the  shell  in  different  regions.  Look  for  layers 
in  the  shell,  an  outer  very  thin  layer,  the  periostracum, 
greenish  or  brownish  in  color.  (This  layer  is  not  always 
seen  since  it  may  have  been  worn  off.)  Next  comes  the 
prismatic  layer,  and  inside  the  nacreous  or  mother-of-pearl 
layer.  The  periostracum  and  the  prismatic  layers  are 
formed  by  the  thickened  edge  of  the  mantle.  Once  formed 
they  cannot  be  added  to  except  at  the  edge  of  the  shell. 


THE  CLAM  127 

The  nacreous  layer  is  secreted  by  the  surfaces  of  the  body 
and  of  the  mantle  in  contact  with  the  shell.  It  may  con- 
tinue to  form  throughout  life.  Is  there  any  proof  that  this 
has  happened? 

4.  Body.— While  working  on  the  following  external  features 
of  the  body  remember  that  while  the  shell  is  properly  a 
part  of  the  body,  an  exoskeleton,  yet  the  fleshy  part  exposed 
by  the  removal  of  the  shell  is  still  the  external  portion  of 
the  body  of  the  animal. 

(a)  Mantle. — This  is  the  thin  membrane  lining  the  shell 
and  covering  the  rest  of  the  body.  How  many  lobes  are 
there?  Are  they  attached  to  the  shell?  If  so,  where,  and 
to  what  extent?  Are  they  joined  to  each  other  at  any  point? 
In  the  posterior  part  of  the  body  observe  that  the  margins 
of  the  mantle  are  hollowed  out  to  form  two  oval  openings, 
a  ventral  incurrent,  and  a  dorsal  excurrent  opening  or  siphon 
(in  Venus  the  mantle  is  fused  to  form  two  tubes).  Deter- 
mine the  cavities  into  which  the  openings  lead.  All  the 
water  that  comes  into  the  shell  enters  through  the  incurrent 
and  all  leaves  by  the  excurrent  opening.  The  cavity  be- 
tween the  mantle  lobes  is  the  mantle  cavity  and  in  it  are 
several  organs. 

(6)  Gills.— Remove  or  turn  back  the  mantle  from  one 
side  and  expose  the  gills,  which  are  thin  membranes  hang- 
ing freely  in  the  mantle  cavity.  How  many  on  each  side 
of  the  body?  Are  they  of  similar  size  and  form?  How 
and  where  are  they  attached  to  the  body?  In  the  female 
the  gill  acts  as  a  brood  pouch  during  the  breeding  season 
and  is  then  greatly  distended  by  the  contained  embryos. 
A  study  of  sections  of  the  gill  may  be  made  to  show  the 
layers  of  which  the  gill  is  composed,  the  water  tubes,  and 
the  bloodvessels. 


128  GENERAL  BIOLOGY 

(c)  Foot.— This  is  the  large  dense  median  part  of  the  body; 
it  forms  a  muscular  wedge  or  keel  by  means  of  which  the 
animal  moves.  Above  the  foot  is  the  softer  visceral  mass 
of  the  body. 

(a)  Muscles.— The  adductor  muscles,  already  noted,  close 
and  hold  the  shell  shut.  There  are  protractor  muscles  for 
pulling  the  foot  and  body  ventrally,  and  extending  it  from 
the  shell.  The  retractor  muscles  draw  these  same  parts  back 
into  the  shell.  Note  their  position  and  the  manner  in  which 
they  work.  (In  Venus  there  is  no  protractor  muscle.) 

(e)  Labial  Palps.— Small,  thin,  leaf-like  organs  behind 
the  anterior  adductor  muscle.  They  aid  in  passing  the 
food  to  the  mouth. 

(/)  Mouth.— Between  the  palps  and  below  the  anterior 
adductor  muscle. 

(</)  Anus.— Opens  into  the  excurrent  or  cloacal  chamber 
it  will  be  found  against  the  posterior  border  of  the  posterior 
adductor  muscle. 

Make  a  drawing  with  the  mantle  removed. 


II.  Internal  Anatomy. 

1.  Circulatory  System.— The  heart  lies  dorsally  between  the 
ligament  and  the  bases  of  the  gills  in  an  oval  sac,  the  pericardial 
cavity.  Dissect  the  pericardium  from  the  dorsal  side  and 
expose  the  cavity  and  the  heart.  The  latter  is  made  up 
of  a  central  muscular  portion,  the  ventricle,  and  two  tri- 
angular lateral  portions,  the  auricles.  Compare  the  auricles 
and  ventricles  in  thickness  of  walls.  If  a  live  clam  is  at 
hand  observe  the  pulsations  of  the  heart.  The  ventricle 
surrounds  the  posterior  portion  of  the  intestine.  There  are 
two  arteries  leaving  the  ventricle,  the  anterior  aorta  and 


THE  CLAM  129 

the  posterior  aorta,  which  carry  blood  to  different  regions. 
Veins  return  the  blood  to  kidneys,  gills,  and  auricles. 

2.  Excretory    System.— The    kidney    is    a    dark    greenish 
gland  on  either  side  of,  and  ventral  to,  the  pericardial  sac. 
Each  kidney  is  a  wide  thin-walled  tube,  doubled  on  itself 
so  that  the  two  ends  are  close  to  each  other.    These  ends 
are  anterior  and  about  opposite,  and  ventral  to,  the  anterior 
end  of  the  pericardium,  while  the  loop  is  posterior  and  lies 
against  the  posterior  adductor  muscle.     One  end   of  the 
kidney  opens  into  the  pericardium,  the  other  into  the  cavity 
of  the  inner  gill. 

3.  Nervous  System.— This  system  is  composed  of  three 
pairs   of   ganglia   connected   by  nerves.    First   locate   the 
visceral  ganglion  just  under  the  posterior  adductor  muscle. 
It  will  appear  as  a  yellowish  mass  under  the  skin  which 
covers  the  muscle.     How  many  nerves  arise  from  this  center? 
To  what  regions  or  organs  do  they  go?    A  small  nerve  on 
either  side  extends  forward  from  this  mass   to  the  brain. 
The  brain  or  cerebral  ganglia  will  be  found  just  under  the 
palps  above  the  mouth,  one  on  either  side.     From  this  nerves 
extend  to  the  adductor  muscle,  mantle  and  palps.    Also 
a  nerve,  the  cerebral  connective,  connects  the  two  ganglia. 

The  pedal  ganglia  are  a  fused  pair  in  the  foot  and  are 
joined  to  the  cerebral  ganglia  by  connectives.  These  ganglia 
will  be  found  while  working  on  the  digestive  system. 

4.  Digestive  System.— With  a  razor  split  the  foot  and  the 
visceral  mass  vertically  in  the  median  line.    Identify  the 
following  parts:    The   mouth   is   immediately   behind   the 
anterior  adductor  muscle.    From  this  a  short  esophagus 
leads  to  the  stomach,  which  is  in  the  dorsal  part  of  the  body. 
Note  the  greenish  digestive  gland,  or  liver,  surrounding  the 
stomach.    The  intestine  extends  from  the  ventral  side  of 
the  stomach  to  the  ventral  part  of  the  foot,  then  poste- 


130  GENERAL  BIOLOGY 

riorly  through  the  foot.  Here  it  turns  on  itself  and  extends 
anteriorly  again,  then  dorsally,  passes  through  the  ventricle 
of  the  heart,  goes  dorsal  to  the  posterior  adductor  muscle, 
and  ends  at  the  anus  in  the  cloacal  chamber. 

5.  The  Reproductive  Organs.— The  ovaries,  or  testes,  are 
present  in  the  visceral  mass  .of  the  body.  They  are  usually 
light  brown  in  color  and  entirely  fill  the  spaces  between  the 
folds  of  the  intestine.  The  ducts  empty  near  those  of  the 
kidney  in  the  supra-branchial  chamber. 

Make  a  large  drawing  to  show  all  the  organs  studied. 
•  6.  Sections  of  the  Body.— In  order  to  show  the  relations 
of  the  various  organs  of  the  body  in  a  manner  as  clear  as 
possible  a  study  of  sections  of  the  body  is  desirable.  These 
are  sections  across  the  entire  body  at  different  regions. 
Make  drawings  of  the  sections  and  show  the  position  and 
arrangement  of  the  organs  that  are  in  the  section.  Show  the 
plan  of  the  organs  by  making  the  drawings  rather  diagram- 
matic. 

(a)  Section  through  the  stomach,  shows  the  stomach, 
mantle,  palps,  liver,  reproductive  organs,  anterior  aorta,  foot. 

(6)  Section  through  the  heart.  Mantle  folds,  gills,  supra- 
branchial  chamber,  intestine  (cut  across  several  times), 
pericardial  cavity,  ventricle,  auricles,  vena  cava  (a  large  vein 
in  the  center  of  the  body  below  the  pericardial  cavity), 
kidney,  ureters,  reproductive  organs. 

(c)  Section  through  the  posterior  adductor  muscle.  Ad- 
ductor muscle,  intestine,  gills,  supra-branchial  cavities,  mantle, 

visceral  ganglia  of  the  nervous  system. 

• 

m.  Physiology. 

1.  Sensitiveness.— Place  a  clam  in  a  dish  of  water  and 
allow  it  to  remain  until  the  shell  opens  and  the  foot  and 


THE  CLAM  131 

edges  of  the  mantle  are  extended.  Use  a  bristle  or  a  delicate 
glass  rod  to  test  the  sensitiveness  of  the  various  parts  ex- 
posed. Determine  whether  foot  or  mantle,  and  which 
portions  of  the  mantle,  are  most  sensitive;  test  especially 
the  edges  of  the  siphons.  What  response  is  made  to  delicate 
tactile  stimuli?  To  stronger  stimuli? 

Sensitiveness  to  chemical  substances  may  be  tested  by 
directing  gentle  currents  from  a  pipette  against  'various 
portions  of  the  body. 

Place  a  specimen  in  a  very  dim  light,  and  when  the  shell 
opens  direct  a  beam  of  light  against  the  body.  Is  there  a 
response  to  this  stimulus?  Place  the  animal  in  sunlight 
or  bright  light  from  some  artificial  source,  and  interpose  a 
screen  between  the  light  and  the  animal,  thus  casting  a 
shadow  upon  the  body.  Note  the  character  of  such  re- 
sponses as  occur. 

2.  Circulation   of   Water.— Introduce    a   few   drops    of   a 
colored  fluid  into  the  water  near  the  posterior  end  of  a  clam 
whose  shell  is  open.    If  the  water  is  drawn  into  the  shell 
observe  the  place  where  it  enters.    Does  the  colored  fluid 
pass  out  of  the  shell  again?    Where  is  the  point  of  exit? 
What  service  to  the  clam  would  there  be  in  such  incurrent 
and  excurrent  movements  of  the  water?    Further  light  on 
this  advantage  will  be  gained  by  observing  a  clam  partly 
buried  in  the  sand  in  the  normal  manner. 

3.  Feeding. — Carefully  insert  a  knife  between  the  valves 
of  a  living  clam  and  cut  the  two  adductor  muscles  where 
they  are  attached  to  the  shell.    Loosen  the  mantle  and 
remove  one  valve  entirely,  thus  exposing  the  body.    Lay 
back  the  mantle,  or  cut  it  loose,  to  expose  gills  and  palps. 
Drop  some  powdered  carmine,  chalk,  or  other  small  solid 
particles  upon  the  surface  of  the  gills  and  note  any  movement 
of  these  particles.    In  what  direction  is  the  movement? 


132  GENERAL  BIOLOGY 

Are  any  of  the  particles  carried  far  enough  forward  to  reach 
the  mouth?  In  the  clam  it  is  by  ciliary  movements  that 
small  organic  particles  are  carried  to  the  mouth,  and  the 
entire  food  is  composed  of  these  particles. 

4.  Heart  Beat.— In  a  specimen  with  one  shell  removed 
observe  carefully  the  region  of  the  body  dorsal  to  the  gills 
and  in  front  of  the  posterior  adductor  muscle.  This  is  the 
position  of  the  heart  and  its  pulsations  may  be  seen  through 
the  delicate  walls  of  the  mantle.  If  care  is  used  one  may 
remove  the  mantle  and  pericardial  walls  and  expose  the 
heart  itself.  When  the  heart  is  exposed  the  pulsations  of 
auricle  and  ventricle  may  be  easily  observed. 


SNAIL. 

HELIX  POMATIA. 

FOR  this  study  the  French  snail  is  suggested,  but  the 
common  pond  snails,  Physa,  Planorbis,  Limnsea  can  be 
used. 

1.  The  Living  Animal.— How  does  the  snail  move?     What 
is  the  shape  of  the  foot?    What  is  the  relation  of  the  foot 
to  the  rest  of  the  body?    What  is  its  relation  to  the  shell? 
The  anterior  part  of  the  foot  is  called  the  propodium,  the 
posterior  portion  the  metapodium,  and  between  these  two 
is  the  mesopodium.    Are  these  regions  sharply  marked  off? 

2.  Head.— At  the  anterior  end  note  the  position  and  form 
of  the  mouth.     Tentacles  are  present  in  this  region.    How 
many?    Size  and  form?    Touch  one  with  a  needle.     What 
happens?    On  the  tentacles  are  small,  pigmented,  glisten- 
ing spots,  the  eyes.     Note  their  position  and  number. 

Locate  the  anal  opening  on  the  right  side  of  the  head.  In 
the  air-breathing  snails  the  respiratory  opening  is  near  the 
anal  opening. 

3.  Shell.— Is  there  a  division  into  valves?     How  many 
turns  does  the  shell  make?     Do  the  shells  vary  in  size? 
Do  the  coils  turn  to  the  right,  or  to  the  left?    Is  the  coiling 
loose  or  close,  flat  or  conical?    The  apex  of  the  shell  is  the 
oldest  part,  the  opening  of  the  shell  is  the  newest  part  of  the 
shell.    In  some  species  one  side  of  the  mouth  of  the  shell 
is  drawn  out  into  a  spout-like  process.    For  what  purpose 
is  this?    In  some  snails  there  is  an  oval  plate  which  closes 


134  GENERAL  BIOLOGY 

the  opening  of  the  shell  when  the  animal  withdraws  into 
it.  Is  there  such  a  plate,  or  operculum,  in  the  form  you  are 
studying? 

The  lines  that  run  parallel  to  the  mouth  of  the  shell  are 
lines  of  growth.  Are  these  uniformly  spaced?  Can  you 
explain  any  variations?  The  whorls  or  turns  of  the  shell 
run  around  a  central  axis,  the  columella.  Observe  the 
columella  and  the  spirals  of  the  shell  in  a  broken  shell. 
Describe  the  relations  of  the  columella  to  the  other  parts 
of  the  shell. 

Make  a  drawing  of  the  snail  from  the  side,  showing  the 
foot,  head,  shell. 


THE  FISH. 

PERCH,  SUCKER,  GUNNER,  OR  OTHER  BONY  FISH. 

WHILE  the  following  directions  have  been  made  with 
reference  to  the  perch,  the  others  named,  or  indeed  almost 
any  species  at  hand  may  be  employed.  It  will  be  especially 
valuable  to  have  a  few  living  specimens,  minnows  or  gold- 
fish, in  a  laboratory  aquarium  for  actual  observations  of 
movements. 

For  dissection  preserved  specimens  are  quite  as  good  as 
those  freshly  killed  or  obtained  from  the  market;  the  last 
are  likely  to  have  been  kept  in  storage  for  some  time  and 
the  internal  organs  are  often  worthless  for  study.* 

I.  General  Features. 

Note  the  shape  of  the  body  and  its  special  differential 
features— head,  tail,  body  proper,  fins.  Are  the  body 
features  sharply  marked?  How  do  they  compare  with 
those  of  the  frog?  Is  the  shape  adapted  to  the  life  and 
habits  of  the  fish?  Note  the  scales,  their  shape  and  arrange- 
ment. Are  they  found  on  all  parts  of  the  body?  How  are 
they  attached  to  the  body?  What  is  their  relation  to  the 
skin?  Examine  a  few  quite  critically  and  decide  whether 
they  are  entirely  naked  and  whether  the  margin  is  smooth 
or  toothed.  A  scale  with  a  smooth,  rounded  outline  is 
called  cycloid,  one  with  a  toothed  margin  is  called  ctenoid; 
to  which  of  these  does  your  specimen  belong? 


136  GENERAL  BIOLOGY 

U.  External  Anatomy. 

1 .  Fins. —How  many  are  there  ?     Where  are  they  located  ? 
Are  they  alike?    Fins  are  said  to  be  paired  or  single.    The 
paired  are  called  pectoral,  occupying  a  position  similar  to 
the  fore  legs  of  the  frog,  and  ventral,  situated  back  of  the 
pectorals  and  on  the  ventral  side  of  the  body.    How  many 
unpaired  fins?    The  one  just  behind  the  vent  is  known 
as  the  anal,  one  occupying   the  median  dorsal  position  is 
the  dorsal.    What  others  are  present  and  how  characterized  ? 
Study  especially  the  structure  of  the  paired  fins  and  com- 
pare with  the  others.     In  what  alike,  in  what  different? 
Study  also  the  ray-like  structure  of  the  supporting  rods 
of  the  fins,  are  they  alike  in  all? 

2.  Mouth.— Note  its  shape  and   size.    Open   and   close 
the  lower  jaw  and  observe  the  movements  of  the  several 
parts.    Are  there  lips?     Identify  the  following  bones  of 
the  upper  jaw:    premaxillary,  forming  the  anterior  and  lateral 
portion  and  extending  backward  to  unite  with  the  maxillary. 
Do  both  bear  teeth?    What  is  the  shape  of  the  teeth?    The 
lower  jaw  is  composed  of  the  dentary  bones.    Do  they  bear 
teeth?    Compare  with  those  of  the  upper  jaw.    Within 
the  mouth  cavity  note  the  shape,  size  and  position  of  the 
tongue. 

3.  The  Eyes.— Observe  their  location,   size   and   shape. 
Test  the  range  of  motion  by  pressing  them  with  the  forceps 
or  finger .    Are  there  eyelids  ? 

4.  Nostrils.— How  many  openings?    What  is  their  shape 
and    position?    Do    the    nostrils    communicate    with    the 
mouth  as  in  the  frog?    Are  they  of  use  in  breathing?    How 
do  they  operate  in  smelling? 

5.  Gill  Openings.— Observe  that  these  openings  are  on 
the  side  of  the  head  and  are  covered  by  flaps,  the  opercles. 


THE  FISH  137 

Can  you  identify  the  subopercle,  preopercle,  interopercle? 
Under  the  opercles  on  the  ventral  side  is  the  branchiostegal 
membrane  and  the  branchiostegal  rays  which  support  the 
membrane.  How  many  are  there?  Raise  the  operculum 
and  examine  the  gills,  their  number  and  arrangement  and 
method  of  support.  On  the  anterior  margin  of  the  gill 
arches  are  teeth  called  gill  rakers.  What  function  can  you 
suggest  for  them?  Press  down  the  tongue  and  observe 
the  effect  upon  gills  and  gill  rakers.  How  does  the  fish 
breathe?  What  motions  are  involved?  Watch  a  fish  in 
the  aquarium  to  find  an  answer  to  these  questions. 

6.  Lateral  Line.— A  series   of  raised,  dot-like   markings 
along  the  sides  of  the  body.    Examine  one  of  the  scales 
which  has  on  it  one  of  the  dots  and  see  what  it  is  like.    The 
lateral  line  has  a  sensory  function. 

7.  Openings.— Just  in  front  of  the  anal  fin  look  for  open- 
ings of  the  anus  and  genital  organs. 

Make  a  drawing  of  the  fish  as  seen  from  the  side. 

m.  Internal  Anatomy. 

Make  a  median  incision  just  in  front  of  the  anus  and  carry 
it  forward  to  the  hinder  border  of  the  gills,  being  careful 
not  to  injure  the  underlying  organs.  Make  cuts  at  right 
angles  so  that  the  flaps  may  be  pressed  to  one  side.  Place 
the  fish  on  its  side  and  work  out  the  internal  organs.  Com- 
pare the  body  cavity  with  that  of  the  frog.  Is  there  a 
thoracic  cavity  distinct  from  an  abdominal? 

1.  Liver.— This  is  a  reddish  organ  of  considerable  size. 
How  is  it  held  in  place?    Is  there  more  than  a  single  lobe 
in  it?     Is  a  gall-bladder  present  as  in  the  frog? 

2.  Stomach.— Raise  the  liver  and  push  it  to  one  side  to 
expose    the    stomach.     From    the    stomach   the    esophagus 


138  GENERAL  BIOLOGY 

leads  to  the  mouth,  and  extending  posteriorly  to  the  anus 
is  the  intestine.  What  is  the  shape  and  size  of  the  stomach? 
Are  there  pyloric  coeca  present?  (These  are  small  finger- 
shaped  filaments,  not  present  in  all  fish.)  Note  the  mesen- 
tery which  supports  the  stomach  and  intestine. 

3.  Spleen.— Observe  its  shape,  color  and  position  in  the 
mesentery. 

4.  Reproductive  Organs.— The  size  of  these  organs  will 
depend  upon  the  season,  i.  e.,  whether  it  be  before  or  after 
the  breeding  period.    At  this  season  they  are  large  and  may 
fill  up  most  of  the  body  cavity.    The  testes  are  usually 
whitish  organs  occupying  a  position  similar  to  that  in  the 
frog.    The  ovaries  may  vary  in  color  and  are  often  bright 
yellow  or  orange.    Determine  the  openings  of  these  organs 
in  the  posterior  part  of  the  body  cavity. 

5.  Kidney.— Along  the  dorsal  wall  of  the  body  cavity  is 
the  large  air  bladder  and  just  above  are  the  twro  kidneys. 
The  kidneys  open  into  the  urinary  bladder  in  the  posterior 
part  of  the  body,  and  this  opens  to  the  outside  just  back 
of  the  anus. 

6.  Heart.— The  heart  is  in  the  extreme  anterior  part  of 
the  body.    Is  it  in  the  same  cavity  as  the  other  organs? 
What  is  the  shape,  and  of  how  many  chambers  is  it  com- 
posed?   If  it  is  desired  to  trace  the  bloodvessels  they  should 
be  injected  as  in  the  frog. 

Make  a  drawing  in  side  view  to  show  the  internal  organs. 

7.  Nervous  System.— This  system  in  the  fish  has  much 
in  common  with  that  of  the  frog.    The  brain  and  cord  can 
be  more  easily  dissected  in  a  specimen  preserved  in  formalin. 

8.  Brain.— Dissect  off  the  skin  and  muscle  and  finally 
the  bony  skull  thus  exposing  the  brain,  and  note:  (a)  the 
cerebral  hemispheres;     (6)  olfactory  lobes;     (<?)  optic  lobes; 
(<f)   thalamencephalon,   between  (a)   and   (c),   upon    which 


THE  FISH  139 

note  the  pineal  body;  (e)  cerebellum;  (/)  medulla  oblongata, 
from  which  continues  the  cord. 

9.  Nerves.— The  ten  pairs  of  cranial  nerves  are  very 
similar  to  those  of  the  frog  and  have  the  same  names.  The 
spinal  nerves  may  be  exposed  and  their  distribution  studied 
as  may  be  directed  by  the  instructor. 

Make  drawings  to  show  the  nervous  system. 


CLASSIFICATION  OF  LIVING  THINGS. 

BOTH  as  a  convenience  in  the  study  of  organisms,  and  as 
in  some  degree  indicative  of  their  genetic  relationships, 
various  efforts  have  been  made  to  arrange  them  under  such  a 
systematic  classification  as  would  serve  these  ends.  The  work 
involved  in  the  foregoing  laboratory  course,  while  dealing 
with  a  few  typical  organisms,  and  devoted  chiefly  to  their 
morphology  and  physiology,  has  also  revealed  unmistakable 
relationships  of  structure  and  function,  which  in  turn  have 
afforded  evidence  of  the  larger  relationships  of  descent. 
That  a  given  kind  or  species  of  animals  has  descended  from 
a  common  line  of  ancestry  is  of  course  universally  recognized. 
That  differing,  but  closely  similar,  species  have  likewise 
descended  from  a  common  ancestor  slightly  more  remote 
is  also  generally  recognized  as  a  fact.  Out  of  the  study  of 
large  series  of  such  facts  has  come  the  conception  of  evolution, 
long  known  to  students  of  biology,  but  first  brought  into 
prominence  by  Lamarck  and  Darwin.  All  modern  sys- 
tems of  classification  have  been  attempts  to  express  the 
facts  of  such  relationships  of  descent  or  evolution.  The 
following  partial  and  abbreviated  tabulation  of  the  animal 
kingdom  may  illustrate,  in  a  general  way,  the  main  features 
of  the  subject. 

PHYLUM    PROTOZOA.— Unicellular,   microscopic    animals, 

or  colonies  of  independent  cells. 

Class  1.  Rhizopoda.— Protozoa  possessing  the  power 
of  thrusting  out  pseudopodia.  A  shell  is  often 
present.  Amoeba,  Arcella,  Heliozoa. 


CLASSIFICATION  OF  LIVING  THINGS  141 

Class  2.  Mastigophora.— Protozoa,  generally  of  small 
size,  provided  with  one  or  more  flagella.  Euglena, 
Peranema,  Pandorina,  Volvox. 

Class  3.  Infusoria.— Protozoa  bearing  cilia,  with  mouth 
and  contractile  vacuole  always  present.  Para- 
mecium,  Vorticella,  Stentor,  Colpoda. 

Class  4.  Sporozoa.— Parasitic  protozoa  without  motile 
organs  in  the  adult;  reproduce  by  spore  formation. 
Plasmodium. 

PHYLUM  PORIFERA.— Radially  symmetrical  animals,  the 
body  wall  containing  many  pores  for  the  entrance 
of  water,  and  usually  supported  by  a  skeleton  of 
spicules. 

PHLYTJM  CXELENTERATA.— Radially  symmetrical  animals 
with  mouth  and  gastro-vascular  cavity,  but  with- 
out ccelom.  Stinging  cells  present. 

Class  1.  Hydrozoa.— Ccelenterates  with  solitary  or 
colonial  polyps,  and  with  an  alternation  of  gen- 
erations. The  medusae  have  a  velum.  Hydra, 
Pennaria,  Obelia,  Gonionemus. 

Class  2.  Scyphozoa.— Ccelenterates  of  considerable  size, 
the  medusa  prominent  but  the  polyps  much  re- 
duced or  absent.    The  edge  of  the  bell  is  lobed  and 
•  a  velum  is  not  present.    Aurelia,  Cyanea. 

Class  3.  Actinozoa.— Polyps  solitary  or  colonial,  with 
esophageal  tube  and  mesenteric  folds.  A  medusa 
generation  is  entirely  lacking.  Sea  anemones  and 
corals. 

PHYLUM  ECHINODERMATA.— Radially  symmetrical  ani- 
mals usually  with  a  pentamerous  arrangement. 
Mouth  and  anus  present,  ccelom  well  developed, 
a  water  vascular  system.  The  body  wall  con- 
tains calcareous  plates  and  usually  bears  spines. 


142  GENERAL  BIOLOGY 

Class  1.  Asteroidea.—  Star-shaped  forms,  the  arms  not 
sharply  marked  off  from  disc  but  with  an  am- 
bulacral  groove  from  which  tube-feet  project. 
Starfish. 

Class  .2.  Ophiuroidea.—  Star-shaped  forms,  the  arms 
sharply  marked  off  from  disc  and  without  am- 
bulacral  groove.  Brittle  stars,  serpent  stars. 

Class  3.  Echinoidea.— Spheroidal  or  discoidal  forms  with 
a  shell  of  closely  fitting  plates  and  with  movable 
spines.  Tube  feet  project  from  five  rows  of  pores 
on  the  shell.  Sea  urchins. 

Class  4.  Holothuroidea.— Elongated  worm-like  echino- 
derms  with  muscular  body  wall  containing  scattered 
plates.  Contractile  tentacles  about  the  mouth, 
and  tube  feet  in  the  form  of  papillae.  Sea  cu- 
cumbers. 

PHYLUM  PLATYHELMINTHES.—  Flattened,  bilaterally  sym- 
metrical, worm-like  animals  with  an  excretory 
system  of  branched  canals  containing  flame  cells. 
Anus  is  not  present,  and  coelom  not  developed. 

Class  1.  Turbellaria.— Free  living  Platyhelminthes  with 
a  ciliated  ectoderm  and  a  centrally  located  muscular, 
protrusible  proboscis.  Planaria. 

Class  2.  Trematoda.—  Parasitic  forms  with  unseg- 
mented,  flattened  body.  Anteriorly  placed  mouth 
and  one  or  more  ventral  suckers.  Liver  fluke. 

Class  3.  Cestoda.—  Elongated,  and  usually  segmented, 
Platyhelminthes  without  mouth  or  digestive  tube. 
Suckers  or  hooks  at  one  end,  and  a  complete  re- 
productive system  in  each  mature  segment.  Tape 
worms. 

PHYLUM  NEMATHELMINTHES.— Elongated,  cylindrical  or 
thread-like  worms  with  unsegmented  body.  Ter- 


CLASSIFICATION  OF  LIVING  THINGS  143 

minal  mouth  and  anus,  coelom  present,  appendages 
wanting.  Body  covered  with  a  heavy  cuticle. 
Free  living  or  parasitic.  Pork  worm  (Trichinella), 
vinegar  eel,  thread  worms, 

PHYLUM  ANNELIDA.— Segmented  worms,  usually  with  a 
well  marked  coelom.  Internal  organs  segmentally 
arranged.  As  a  rule  chitinous  setae  are  embedded 
in  the  skin. 

Class  1.  Chaetopoda.  —  Annelida  with  conspicuous  setae. 
The  well  marked  coelom  divided  by  septa.  Earth- 
worm, Nereis. 

Class  2.  Hirudinea.— Elongated,  flattened  annelida  with 
anterior  and  posterior  suckers,  without  seise  and 
with  median  genital  openings.  Coelom  much 
reduced.  Leeches. 

Class  3.  Gephyrsea.  Unsegmented  worm-like  animals 
with  a  spacious  ccelom  not  divided  by  septa,  an 
anterior  anus  and  a  single  pair  of  nephridia.  Setae 
absent. 

PHYLUM  MOLLUSCA.— Bilaterally  symmetrical,  unseg- 
mented  animals,  with  a  ventral  foot,  a  mantle  fold, 
and  usually  a  univalve  or  bivalve  shell.  The 
central  nervous  system  consists  of  a  circum-eso- 
phageal  ring. 

Class  1.  Lamellibranchiata. — Symmetrical  mollusca  with- 
out head;  with  bilobed  mantle,  bivalve  shell,  and 
usually  with  lamellate  gills.  Clams,  mussels, 
oysters. 

Class  2.  Gastropoda.— Asymmetrical  mollusca  with  a 
distinct  head  usually  bearing  tentacles,  a  muscular 
creeping  foot,  a  continuous  mantle  fold  and  usually 
a  coiled  shell  of  one  piece.  Snails. 


144  GENERAL  BIOLOGY 

Class  3.  Cephalopoda.—  Mollusca  with  a  well  marked 
head,  a  circle  of  arms  bearing  suckers  around  the 
mouth,  and  well  developed  eyes.  There  is  a  heavy 
muscular  mantle  fold;  the  nervous  system  is  con- 
centrated in  the  head.  Squid,  octopus. 
PHYLUM  ARTHROPODA.— Segmented  animals  with  a 
firm  external  skeleton  and  jointed  appendages. 

Class  1.  Crustacea.— Aquatic  arthropods  breathing  by 
means  of  gills,  with  two  pairs  of  antennae  and 
.numerous  pairs  of  biramous  appendages  on  thorax 
and  abdomen.  Crayfish,  lobster,  crab,  water  flea, 
barnacles. 

Class  2.  Myriapoda.— Worm-like  arthropods  with  numer- 
ous similar  segments  bearing  similar  appendages. 
One  pair  of  antennae,  breathe  by  means  of  tracheae. 
Millipeds,  centipedes. 

Class  3.  Insecta.— Arthropoda  with  the  adults  usually 
bearing  three  pairs  of  legs  and  two  pairs  of  wings; 
body  divided  into  head,  thorax  and  abdomen; 
single  pair  of  antennas;  breathe  by  tracheae.  A 
metamorphosis  is  common  in  the  life  history.  Fly, 
mosquito,  beetle,  grasshopper,  bee. 

Class  4.  Arachnida.— Arthropoda  without  antennae,  with 
four  pairs  of  legs  and  two  pairs  of  mouth  parts. 
Body  divided  into  cephalothorax  and  abdomen. 
Breathe  by  means  of  trachea?  and  book  lungs. 
Spiders,  mites,  scorpions. 

PHYLUM  VERTEBRATA.— Animals  with  dorsal  brain  and 
cord,  enclosed  in  an  unsegmented  skull  and  a  seg- 
mented vertebral  column.  Red  blood;  usually 
with  two  pairs  of  appendages. 

Class  1.  Pisces.— Aquatic  vertebrates  breathing  by 
means  of  gills;  typically  with  two  paired  and  other 
unpaired  fins.  Fishes. 


CLASSIFICATION  OF  LIVING  THINGS  145 

Class  2.  Amphibia.— Cold  blooded  vertebrates  with 
naked  scaleless  skin.  Breathe  by  lungs  in  adult 
life  commonly,  the  larvse  breathe  by  gills.  Heart 
with  two  auricles  and  a  single  ventricle.  Frogs, 
toads,  salamanders. 

Class  3.  Reptilia.— Cold  blooded  scaly  vertebrates. 
Breathe  by  lungs;  heart  with  auricles  and  two 
imperfectly  separated  ventricles.  Snakes,  turtles, 
alligators,  lizards. 

Class  4.  Aves.— Warm  blooded,  oviparous,  bipedal 
vertebrates  covered  with  feathers.  The  chambers 
of  the  heart  are  completely  separated.  The  an- 
terior appendages  have  the  form  of  wings.  Birds. 

Class  5.  Mammalia.— Warm  blooded,  hairy  vertebrates. 
Viviparous;  mammary  glands  with  which  they 
suckle  the  young.  Red  blood  corpuscles  non- 
nucleated.  Mammals. 


10 


APPENDIX. 


Collection  and  Preparation  of  Material. 

Amoeba.— While  amoeba  has  a  wide  distribution,  -in  no 
place  is  it  very  abundant,  nor  are  culture  methods  as  success- 
ful as  with  other  protozoa.  By  putting  Elodea,  Cerato- 
phyllum,  or  other  water  plants,  into  a  shallow  dish  with  a 
small  amount  of  water  and  allowing  the  plants  to  decay, 
amoebae  may  often  be  found  in  some  abundance  in  the  slimy 
sediment.  The  slime  on  lily  pads  often  contains  amoebae. 
Occasionally  amoebae  will  be  extremely  abundant  in  the 
scum  on  a  freshly  started  hay  infusion,  especially  when 
pond  weeds  have  been  present  in  the  infusion. 

Par amecium.— Into  a  hay  infusion  twenty-four  hours  old 
(that  made  from  dry  timothy  hay  is  best),  place  some  water 
and  organic  matter  from  almost  any  pond  or  swamp.  After 
about  a  week  Paramecium  will  be  found  in  abundance.  Or 
fill  a  jar  half  full  of  Elodea  or  other  pond  weeds,  cover  with 
water  and  allow  the  plants  to  decay.  Do  not  place  the 
jars  in  the  direct  sunlight. 

To  keep  a  culture  in  vigorous  condition  remove  some  of 
the  old  hay  and  about  one-third  of  the  water,  and  add  fresh 
hay  and  water,  every  two  or  three  days.  If  several  cultures 
are  running  and  are  changed  on  different  days  one  may  have 
vigorous  cultures  of  Paramecium  constantly. 

Conjugating  paramecia  are  often  obtained  a  few  days  or 
a  week  after  a  fresh  culture  is  started,  if  the  culture  has  been 
started  by  bringing  in  Paramecium  from  outside. 


148  GENERAL  BIOLOGY 

Paramecium  probably  never  encysts  and  a  hay  infusion 
made  as  sometimes  directed,  but  not  inoculated  from  some 
source  containing  the  animals,  will  not  give  rise  to  para- 
mecia.  The  culture  must  be  inoculated  from  an  old  culture, 
or  the  animals  must  be  introduced  from  outside  sources. 

To  kill  Paramecium  hot  Worcester's  fluid  is  probably  the 
best.  A  round  bottomed  vial  is  filled  one-third  full  from  a 
good  culture,  with  as  many  of  the  animals  and  as  little  fluid 
as  possible.  Fill  the  vial  to  the  top  with  hot  Worcester's 
fluid  and  allow  to  stand  fifteen  minutes,  during  which  time 
the  animals  will  settle  to  the  bottom.  With  a  pipette  draw 
off  as  much  of  the  killing  fluid  as  possible  and  add  water  to 
wash,  using  several  changes  and  stirring  up  the  mass  of 
paramecia  as  little  as  possible.  Stain  in  hematoxylin 
rather  heavily,  destain  with  weak  acid,  or  acid  alcohol,  until 
the  color  is  very  faint  except  in  the  nucleus.  WTash  in  water, 
dehydrate,  clear  and  mount  on  a  slide  in  balsam.  Support 
the  cover  glass  to  prevent  crushing  the  animals. 

Vorticella.— If  sticks,  leaves,  and  pond  weeds  are  placed 
in  a  jar  and  allowed  to  stand  a  day  or  two  a  scum  will  form 
on  the  water,  and  in  this  scum  Vorticella  will  often  be  abun- 
dant. In  such  fresh  cultures  large  specimens  are  usually 
found.  The  methods  used  for  continuing  Paramecium 
cultures  will  be  fairly  successful  for  Vorticella.  Similar 
metiiods  of  killing  and  staining  may  be  used  but  are  not 
very  successful,  on  account  of  the  contraction  which  usually 
takes  place  in  Vorticella. 

Hydra.— In  ponds,  swamps,  and  slow  moving  streams 
covered  with  "duck-weed'"'  (Lemna)  green  hydra  will  often 
be  abundant  in  spring  and  summer.  Brown  hydra  is  more 
often  found  in  larger  ponds  and  lakes  on  Sagittaria  and  pond- 
lily  leaves.  Place  the  plants,  in  both  cases,  in  jars  and  set 
in  a  bright  place,  but  not  in  the  direct  sunlight.  Within  a 


APPENDIX  149 

few  days  hydra,  if  present,  will  be  found  on  the  side  of  the 
jar  toward  the  light.  In  the  autumn  secure  leaves  from 
the  bottom  of  the  pond  and  some  of  the  surface  mud. 

Hydra  will  nourish  if  the  jar  is  kept  supplied  with  an 
abundance  of  "water-fleas,"  Daphnia,  Cyclops,  Cypris, 
etc.,  and  budding  will  be  abundant  on  the  hydras.  If  the 
food  supply  is  allowed  to  diminish  reproductive  organs  will 
often  begin  to  appear. 

To  kill  hydra  expanded  remove  a  single  specimen  from 
the  aquarium  with  a  pipette  and  place  in  a  perfectly  clean 
watch  glass  with  only  a  small  amount  of  water.  When  the 
animal  in  the  watch  glass  is  well  expanded  dash  hot  Wor- 
cester's fluid,  or  hot  Bouin's  fluid,  over  it  and  allow  to  stand 
ten  minutes.  The  animal  may  then  be  washed  and  treated 
for  further  use  by  staining  or  embedding  for  sections.  Handle 
very  carefully  since  the  killing  fluid  makes  them  rather  brittle. 
If  whole  mounts  are  desired  a  light  stain  with  hematoxylin 
is  good.  When  mounting  support  the  cover  glass  to  pre- 
vent crushing. 

Hydroids,  Jelly-fish.— If  these  are  collected  the  jelly-fish 
should  be  preserved  in  formalin.  Obelia  should  be  nar- 
cotized with  magnesium  sulphate  before  killing,  to  get  the 
hydranths  expanded.  It  is  well  to  have  the  hydroids  killed 
in  some  killing  fluid  and  preserved  in  alcohol,  though  for 
general  external  study  preservation  in  formalin  is  satis- 
factory. To  make  whole  mounts  of  the  hydroids  proceed 
as  for  hydra. 

Earthworm.— In  the  spring  and  early  summer  after  a 
soaking  rain  large  earthworms  can  easily  be  obtained  at 
night.  With  a  light  examine  the  ground,  preferably  in  a 
garden  or  where  there  is  little  grass.  Place  the  worms  in 
a  can  with  a  little  soil  until  morning. 

To  preserve  put  the  worms  in  a  dish  or  pan  with  enough 


150  GENERAL  BIOLOGY 

water  to  just  cover  them  and  add  a  few  drops  of  alcohol 
every  few  minutes.  After  several  hours  they  will  be  found 
to  be  motionless  and  should  not  respond  to  tactile  stimuli. 
They  should  now  be  laid  out  straight  and  flat  in  a  disk  of 
weak  alcohol  and  allowed  to  remain  for  not  more  than  four 
hours.  They  are  then  to  be  placed  in  80  per  cent  alcohol, 
or  better  a  mixture  of  alcohol  and  10  per  cent  formalin  for 
preservation.  The  worms  should  be  kept  straight  in  the 
preservative  since  they  are  much  easier  to  study  when  in 
this  condition. 

A  somewhat  clearer  demonstration  of  setae  and  of  external 
openings  can  be  made  on  worms  killed  (after  narcotizing) 
in  1  per  cent  chromic  acid.  After  twenty-four  hours  in  the 
chromic  acid,  wash  overnight  in  water  and  preserve  in 
alcohol.  These  are  not  so  good  for  internal  study. 

For  sectioning  place  worms  in  a  dish  with  moist  filter 
paper  and  leave  for  several  days  until  they  void  clean  filter 
paper  instead  of  dirt.  The  digestive  tract  is  now  in  con- 
dition for  sectioning.  Narcotize  with  alcohol  (or  chloral 
hydrate,  or  chloretone)  and  when  motionless  cut  into  small 
pieces  and  fix  in  Bouin's  fluid. 

It  is  very  easy  to  keep  earthworms  alive  all  winter  with 
little  or  no  trouble.  In  a  wooden  box  filled  with  moist 
loamy  soil  place  a  number  of  worms  and  keep  the  box  in 
a  cool  place.  Every  few  days  leaves,  pieces  of  apple,  etc., 
should  be  spread  on  the  surface  for  the  worms  to  feed  upon. 
Cover  the  box  with  a  heavy  cloth  (burlap)  which  is  kept 
moist  and  the  soil  will  need  very  little  attention.  If  the 
soil  should  appear  dry  it  must  be  sprinkled  enough  to 
thoroughly  moisten  it. 

Grasshopper.— The  larger  grasshoppers  are  best  for  study 
on  account  of  their  size,  and  are  necessary  if  much  internal 
study  is  to  be  made.  But  for  the  study  of  external  features 


APPENDIX  151 

the  small  red-legged  locust  (Melanoplus  femur-ntbrum) 
will  be  satisfactory.  Some  of  these  should  be  alive  in  the 
laboratory  for  study  of  the  habits  of  living  specimens. 
Preserve  insects  in  alcohol,  rather  than  formalin. 

Crayfish.— Crayfish  may  be  purchased  alive  from  dealers, 
or  collected.  If  they  are  collected  in  the  autumn  and  placed 
in  a  tank  (or  tub)  with  water  and  kept  in  a  cool,  rather  dark 
place,  they  will  live  for  a  long  time.  If  running  water  is 
not  available  the  water  in  the  tank  should  be  changed 
occasionally,  especially  if  a  scum  appears  on  it. 

For  demonstrating  water  currents  over  the  gills  use 
powdered  carmine,  India-ink,  methylene  blue,  etc.,  and 
drop  along  the  edge  of  the  carapace.  A  piece  of  the  carapace 
at  the  side  of  the  mouth  parts  may  be  removed  in  the  living 
animal*  if  carefully  done,  and  the  movement  of  the  gill 
bailer  demonstrated. 

The  heart  and  larger  bloodvessels  are  easily  injected  with 
a  thin  starch  mass.  Either  remove  a  piece  of  the  carapace 
and  with  syringe  gently  inject  the  mass  into  the  heart,  or 
if  the  position  of  the  heart  is  determined  the  carapace  and 
heart  may  be  pierced  with  the  cannula  of  the  syringe. 

For  preservation  cut  away  a  small  piece  of  the  carapace 
on  the  dorsal  side  to  permit  the  entrance  of  the  preservative. 
Alcohol  is  a  better  preservative  than  formalin  since  the  acid 
in  the  latter  dissolves  out  some  of  the  mineral  matter  of  the 
shell,  and  leaves  an  undesirable  scum  on  the  liquid  and 
about  the  animals. 

Clam.— The  fresh  water  clam  is  much  easier  and  better 
for  study  than  the  salt  water  forms.  Use  the  larger  forms. 
If  the  valves  are  forced  open  and  a  wedge  of  wood,  or  a 
pebble,  is  placed  between  to  prevent  closing,  the  animals 
may  be  thrown  directly  into  formalin  for  preservation.  They 
may  be  kept  alive  for  some  time  in  a  cool  place  with  running 
water. 


152  GENERAL  BIOLOGY 

To  harden  for  making  macroscopic  sections  across  the 
body.,  .wedge  -the  valves  open,  place  in  .1  per  cent  chromic 
acid  for  a  day  or  so.  Wash  in  water  and  preserve  in  alcohol. 
When  ready,  for  sectioning  remove  the  valves  carefully, 
place  the  body  of  the  clam  on  a  piece  of  cork  or  wax  and 
with  a  razor  or  brain  knife  make  sections  from  |  to  \  inch 
thick. 

Snail.— If  the  edible  snail  (French  or  Roman  snail)  is  used 
it  must  be  purchased  from  dealers. 

Frog.— Any  of  the  common  frogs  will  do,  though  they 
should  be  as  large  as  possible.  For  the  study  of  living 
specimens  in  the  winter,  material  must  be  obtained  from 
dealers  unless  it  has  been  collected  earlier  and  kept  alive 
in  a  tank.  .  If  the  animals  are  placed  in  a  tank  and  kept  in 
a  cool  place  in  running  water,  or  the  water  frequently  changed, 
and  there  is  a  platform  or  float  on  which  they  may  rest,  it 
is  possible  to  keep  them  alive  all  winter.  During  cold 
weather  food  is  not  needed.  To  preserve,  anesthetize  with 
ether  or  chloroform  and  place  in  5  per  cent  formalin.  Al- 
cohol is  not  so  good  as  a  preservative  for  these  forms. 

For  demonstration  of  circulation  in  the  web,  narcotize 
the  frog  with  chloretone,  place  on  a  plate  of  glass  and  cover 
body  with  damp  cloth.  Hold  the  toes  spread  apart  with 
bent  pins  held  in  place  against  the  glass  with  masses  of 
putty  or  wax. 

To  inject  the  bloodvessels  for  the  study  of  the  arterial 
system  proceed  as  follows:  Anesthetize  the  frogs  with 
chloroform  or  ether  (the  latter  leaves  them  in  somewhat 
better  condition),  remove  a  piece  of  the  pectoral  girdle  from 
over  the  heart,  and  remove  the  pericardium.  With  the 
scissors  cut  a  slit  in  the  ventricle,  insert  the  cannula  through 
the  ventricle  into  the  truncus  arteriosus,  and  with  a  steady, 
gentle  pressure  fill  the  arteries  with  the  injection  mass 


APPENDIX  153 

(formula  for  injection  mass  on  page  159).  No  ligature  will 
be  needed  since  the  valves  of  the  truncus  prevent  the  back- 
ward flow  of  the  mass.  During  the  injection  of  the  arteries 
the  blood  has  been  forced  into  the  veins,  and  because  of 
this  it  is  possible  to  follow  the  veins  fairly  well  without  in- 
jecting them.  After  the  injection  is  complete,  the  blood 
and  excess  injection  mass  should  be  wrashed  off,  and  the 
frogs  preserved  in  formalin. 

For  the  study  of  the  histology  of  the  frog  examine  fresh 
tissues  in  normal  salt  solution.  For  sections  of  the  spinal 
cord  fix  in  10  per  cent  formalin,  embed  in  paraffin  and  make 
rather  thick  sections.  Borax  carmine  or  hematoxylin  are 
good  stains  to  show  the  general  form  and  something  of  the 
cells.  For  a  sharp  distinction  of  the  white  and  gray  sub- 
stances Weigert's  hematoxylin  method  for  medullated 
nerves  gives  beautiful  results.  (See  directions  in  books  on 
technic.  The  mordant  of  copper  acetate  may  be  used  after 
the  sections  are  on  the  slide.)  For  sections  of  the  stomach 
cut  the  organ  into  two  parts,  rinse  in  salt  solution  and  fix 
twTenty-four  hours  in  Zenker's  fluid.  Hematoxylin  and 
Congo-red  are  good  stains  to  differentiate  the  tissues. 

In  the  spring  get  spawn  from  ponds  and  place  small  masses 
in  jars  for  the  study  of  the  development.  Water  plants  in 
the  jars  will  help  to  aerate  the  water.  If  the  water  at  any 
time  appears  turbid,  change.  The  tadpoles  may  be  kept 
for  some  time  after  hatching  if  the  aquaria  are  kept  supplied 
with  algae  or  other  water  plants. 

Preparation  and  Mounting  of  Slides. 

To  get  the  best  results  in  mounting  small  objects  or 
sections,  the  animal  or  tissue  must  be  properly  prepared. 
It  must  be  killed  quickly  so  that  the  constituents  of  the 


154  GENERAL  BIOLOGY 

cells  are  fixed  in  a  normal  condition.  Usually  some  harden- 
ing of  the  tissue  takes  place  during  the  fixation,  but  if  not 
the  alcohol  used  for  preservation  will  also  accomplish  this 
purpose. 

Killing  and  fixing  reagents  are  numerous;  some  are  good 
for  a  special  purpose  only  and  others  have  a  wider  use. 
Those  mentioned  among  the  reagents  are  good,  easily  used, 
and  satisfactory  for  any  of  the  work  demanded  in  a  begin- 
ning course. 

After  fixation  the  tissue  must  be  washed  to  remove  the 
excess  of  the  reagent,  and  then  preserved  in  80  per  cent 
alcohol  until  wanted  for  use.  Since  this  procedure  has  a 
bleaching  effect  on  the  tissues,  dyes  are  used  to  stain  the 
object  to  make  it  more  easily  seen.  If  sections  are  desired 
it  is  necessary  to  embed  the  tissue  or  organ  in  paraffin  or 
other  medium  to  support  the  softer  mass  while  the  sections 
are  being  made.  Directions  for  this  must  be  had  from  books 
on  histological  technic. 

For  examination  of  living  tissues  normal  salt  solution  is 
the  medium  used;  for  fresh  water  animals,  if  alive,  water 
is  used;  preserved  animals  are  examined  in  the  solution 
in  which  they  are  preserved.  Glycerin  is  used  if  it  is  desired 
to  render  the  objects  somewhat  transparent.  They  may 
be  placed  in  the  glycerin  from  water,  alcohol,  or  formalin 
directly. 

If  a  permanent  mount  is  desired  the  object  is  usually 
first  stained,  then  dehydrated  by  placing  for  about  an  hour 
in  alcohol  of  various  grades  (35  per  cent,  50  per  cent,  70 
per  cent,  80  per  cent,  95  per  cent).  If  absolute  alcohol  is 
at  hand  they  should  be  placed  in  this  for  an  hour  to  com- 
plete the  dehydration.  To  remove  the  alcohol  some  fluid, 
usually  an  oil,  is  used  which  will  mix  with  the  alcohol  and 
also  with  the  balsam  which  is  used  to  complete  the  mounting. 


APPENDIX  155 

Cedar-wood  oil,  clove  oil,  creosote,  xylol  and  benzol  are  some 
of  the  common  fluids  used  for  this  purpose.  Not  only  do 
they  remove  the  alcohol  but  they  also  render  the  object 
transparent  and  are  therefore  called  clearing  agents.  Cedar- 
wood  oil  and  xylol  are  the  most  commonly  used  of  the  oils 
mentioned.  When  the  object  has  become  transparent  it 
is  placed  on  a  slide,  the  excess  of  oil  allowed  to  run  off,  or 
removed  with  filter  paper,  then  a  drop  of  Canada  balsam 
placed  on  the  object  and  this  is  covered  with  a  thin  cover 
glass  which  is  allowed  to  gently  settle  on  the  object.  When 
the  balsam  has  hardened  the  object  is  permanently  fixed. 
If -absolute  alcohol  is  not  at  hand  for  the  final  dehydration, 
place  the  object  from  95  per  cent  alcohol  directly  into  a 
mixture  of  one-third  beechwood  creosote  and  two-thirds 
xylol,  or  into  the  same  proportions  of  xylol  and  melted  car- 
bolic acid  crystals.  Cedar  oil  and  oil  of  cloves  will  also  clear 
directly  from  95  per  cent  alcohol.  After  the  object  has 
been  cleared  proceed  as  directed  in  the  previous  paragraph. 
Before  a  slide  is  laid  away  it  should  be  labeled  as  to  the 
animal,  or  part,  or  tissue;  how  fixed;  how  stained;  date 
and  name  of  person  making  the  preparation. 

Reagents. 

Acetic  Acid.— A  solution  of  0.2  per  cent  to  1  per  cent 
applied  to  fresh  tissues  will  render  the  nuclei  visible. % 

Alcohol.  —This  is  the  most  used  reagent  in  the  laboratory 
and  should  be  kept  on  hand  in  abundance,  made  up  in 
various  strengths.  Alcohol  is  rather  expensive  if  bought  in 
small  amounts  from  a  druggist  or  ordinary  dealer,  but  it 
can  be  purchased,  for  scientific  purposes,  with  the  revenue 
tax  remitted.  The  collector  of  internal  revenue  of  the 
district,  or  the  Federal  Treasury  Department  can  give 


156  GENERAL  BIOLOGY 

directions  for  its  purchase.  Denatured  alcohol  may  be 
used  and  is  cheaper,  and  about  as  satisfactory,  as  the  regular 
alcohol.  Grain  or  ethyl,  and  not  wood  or  methyl  alcohol, 
should  be  used ;  the  latter  is  poisonous. 

Commercial  alcohol  is  ordinarily  about  95  per  cent  in 
strength.  To  make  various  grades  from  the  commercial 
product,  fill  a  graduate  with  95  per  cent  to  the  mark  which 
indicates  the  desired  strength,  and  then  add  water  up  to 
95  cc  (e.  g.,  to  make  70  per  cent  from  95  per  cent  take  70 
cc  of  alcohol  and  add  water  up  to  95  cc) .  It  is  well  to  have 
alcohol  of  the  following  grades  prepared:  35  per  cent,  50 
per  cent,  70  per  cent,  80' per  cent,  95  per  cent.  These  will 
be  used  in  the  preparation  of  slides.  For  preservation  70 
per  cent  or  80  per  cent  is  used. 

Acid  Alcohol.— Of  70  per  cent  alcohol  take  99  cc  and  of 
concentrated  hydrochloric  acid  Ice.  Used  chiefly  for 
destaining  tissues. 

Anilin  Dyes.— For  staining,  these  may  be  dissolved  in 
water,  or  in  alcohol  of  any  grade.  They,  are  most  com- 
monly used  in  aqueous  solutions.  It  is  better  to  stain  for 
some  time  with  a  weak  solution,  than  for  a  brief  period 
with  a  strong  mixture.  Some  of  the  stains  will  be  removed 
by  alcohol,  and  experience,  or  reference  to  some  book  on 
technic,  must  show  the  best  methods  of  use.  The  com- 
mon dyes  used  for  the  staining  of  the  cytoplasm  are:  eosin, 
congo-red,  acid  fuchsin,  light  green,  orange  G. 

Benedict's  Solution.— Used  in  the  same  way  as  Fehling's 
solution  for  demonstrating  the  presence  of  grape  sugar. 
This  solution  is  said  not  to  deteriorate  on  long  standing. 

Sodium  citrate 173  g. 

Sodium  carbonate 100  g. 

Dissolve  in  600  cc  water,  using  heat.  Filter  and  make  up 
to  850  cc  with  water.  Dissolve  17.3  g.  of  copper  sulphate 


APPENDIX  157 

in  100  cc  water  and  make  up  to  150  cc  with  water.  Add 
the  cupric  sulphate  solution  to  the  carbonate-citrate  solution 
slowly,  stirring.  The  mixed  solution  is  ready  for  use. 

Borax  Carmine.— Dissolve  4  g.  borax  in  100  cc  water.  Add 
1  g.  carmine  and  dissolve  it  with  heat.  Cool  and  add  to 
the  solution  100  cc  of  70  per  cent  alcohol.  Filter  after 
twenty-four  hours.  A  good  stain  for  large  objects  and  for 
tissues  in  bulk.  Use  the  stain  twenty-four  hours,  and 
differentiate  with  acid  alcohol. 

Bouin's  Fluid. 

Saturated  aqueous  picric  acid 75  cc 

Commercial  formalin 25  " 

Glacial  acetic  acid •    .       5   " 

It  is  best  to  add  the  acetic  acid  just  before  using.  Kill 
the  tissue  four  to  twenty-four  hours,  wash  in  50  per  cent 
alcohol,  preserve  in  80  per  cent  alcohol.  This  is  one  of  the 
best  of  the  killing  fluids  for  general  use. 

Chloretone.— Make  a. saturated  solution  in  water.  Used 
for  narcotizing  animals.  In  some  cases  it  may  be  sprayed 
on  top  of  the  water  which  contains  the  animals.  For  nar- 
cotizing frogs  for  demonstrating  the  circulation  of  the  blood 
in  the  web  the  following  method  has  proved  satisfactory: 
With  a  pipette  inject  about  2  cc  into  the  stomach  through 
the  esophagus.  If  after  twenty  minutes  the  animal  is  not 
quiet  repeat  the  dose.  The  animal  will  remain  quiet  for 
hours,  but  will  be  recovered  within  twenty-four  hours. 

Chloriodide  of  Zinc. 

Chloride  of  zinc 30 . 0    g. 

Potassium  iodide 5 . 0    g. 

Iodine 0.89g. 

Dissolve  the  above  ingredients  in  about  15  to  20  cc  distilled 
water.  The  solution  does  not  keep  long,  and  should  be 
kept  in  the  dark.  Used  as  a  test  for  cellulose. 


158  GENERAL  BIOLOGY 

Fehling's  Solution. 

A.  Copper  sulphate  34.65  g.  dissolved  in    ...     500  cc  of  water 

B.  Sodium  or  potassium  hydroxide      ....      125  g. 
Sodio-potassium  tartrate  (Rochelle  salts)         .     173  g. 

Dissolve  in  500  cc  of  water. 

Keep  solutions  separate  until  ready  to  use.  Just  before 
using  mix  equal  parts  of  A  and  B.  This  solution  is  used  to 
test  for  the  presence  of  grape  sugar. 

Formalin.— Commercial  formalin  is  a  solution  of  formalde- 
hyde gas  in  water  (40  per  cent).  To  use,  this  is  considered 
as  absolute  and  a  5  or  10  per  cent  solution  made  (e.  g.,  to 
make  5  per  cent  formalin  mix  5  cc  of  commercial  formalin 
and  95  cc  of  water).  For  practically  all  organisms,  plant 
and  animal,  used  in  the  laboratory  or  in  the  museum  5  per- 
cent formalin  is  an  efficient  preservative  and  for  most  things 
as  satisfactory  as  alcohol.  If  the  tissues  are  very  watery 
the  solution  should  be  changed  after  twenty-four  hours. 

Glycerin.— Use  pure  or  diluted  with  equal  parts  of  water 
or  alcohol.  Useful  as  a  clearing  agent  and  as  a  temporary 
mounting  medium. 

Hematoxylin  (Delafield's).— Hematoxylin  crystals  1  g.  di,s- 
solved  in  10  cc  of  strong  alcohol.  Add  this  slowly  to  100  cc 
of  saturated  aqueous  solution  of  ammonium  alum,  stirring. 
Expose  this  solution  to  the  air  for  several  weeks  to  ripen. 
Filter  and  add  25  cc  of  glycerin  and  25  cc  of  methyl 
alcohol. 

Hematoxylin  is  one  of  the  most  satisfactory  stains  for 
tissues;  it  is  a  nuclear  stain.  To  use,  dilute  the  stain  and 
let  it  act  until  the  tissue  is  dark  and  overstained.  Destain 
with  acid  alcohol  or  with  very  dilute  aqueous  hydrochloric 
acid  (1  per  cent  of  acid  or  less,  in  water).  The  slides  hold- 
ing the  sections  must  now  be  washed  for  at  least  five  minutes 
in  running  water,  to  remove  the  acid  and  restore  the  blue 


APPENDIX  159 

color.  Now  counterstain  the  sections,  if  desired,  dehy- 
drate, clear  and  mount. 

Injection  Mass.— The  following  is  one  of  the  best  masses 
for  injecting  bloodvessels. 

Dry  corn  starch 1  Ib. 

Chloral  hydrate  (2£  per  cent) 600  cc 

Alcohol  (95  per  cent) 150   " 

Color 150  " 

The  chloral  hydrate  and  alcohol  of  the  above  may  be  re- 
placed by  750  cc  of  5  per  cent  formalin;  the  resulting  mass 
appears  to  act  as  well  as  the  one  above.  To  make  the 
color  take  about  50  g.  of  dry  insoluble  color,  such  as  chrome 
yellow  or  vermilion,  grind  in  a  mortar  with  50  cc  of  glycerin 
and  50  cc  of  alcohol  (95  per  cent).  Mix  the  color  and  the 
liquid  and  slowly  stir  in  the  starch  to  make  a  homogeneous 
mass.  If  the  mass  appears  to  be  getting  too  thick  use  less 
starch,  if  too  thin  add  more  starch.  Before  using  the  mass 
should  be  strained  through  two  thicknesses  of  cheesecloth, 
to  remove  all  particles  which  might  clog  the  cannula  or 
artery.  The  injection  mass  does  not  spoil  upon  standing, 
but  must  be  well  stirred  before  using. 

Iodine  Solution.— Dissolve  potassium  iodide  in  distilled 
water  to  saturation,  then  saturate  this  solution  with  metallic 
iodine.  To  use  dilute  with  several  volumes  of  water.  May 
be  used  as  a  stain  for  protoplasm,  but  chiefly  used  for  starch 
test. 

Lime  (or  Baryta)  Water.— Shake  up  a  little  quick  lime 
(or  barium  oxide  for  baryta  water)  in  water  and  allow  the 
mixture  to  settle.  Decant  or  filter  the  clear  liquid.  In  the 
presence  of  carbon  dioxide  this  clear  liquid  will  become 
milky,  or  will  show  a  white  precipitate. 

Lyons  Blue.— This  is  one  of  the  anilin  dyes.  An  alcoholic 
solution  should  be  made.  This  is  used  as  a  contrast  stain 
with  borax  carmine. 


160  GENERAL  BIOLOGY 

Methyl  Green.— A  strong  aqueous  solution  (1  per  .cent) 
with  1  per  cent  of  acetic  acid.  An  excellent  stain  for  fresh 
tissues.  Stains  the  nucleus  only,  stains  rapidly  and  does 
not  overstain. 

Methylene  Blue.— Pure  methylene  blue  added  to  water  to 
make  a  light  blue  tint  will  stain  parts  of  the  living  animals 
contained  in  the  water.  Several  hours  are  usually  neces- 
sary. Does  not  affect  the  animals,  but  the  stain  should 
be  pure  for  this  purpose. 

Normal  Salt  Solution.— Dissolve  7  g.  of  common  salt  in 
1000  cc  of  water.  This  solution  is  used  as  a  medium  for 
the  examination  of  fresh  tissues.  The  concentration  ap- 
proaches that  of  the  lymph,  and  tissues  and  cells  in  it  are 
not  distorted  as  they  would  be  in  water. 

Pasteur's  Solution. 


Ammonium  tartrate  . 
Potassium  phosphate 
Calcium  phosphate    . 
Magnesium  sulphate 
Cane  sugar 
Water  to  make 


50  g. 

10  g. 

lg. 

1  g. 

750  g. 

5000  cc 


This  solution  is  used  as  a  culture  medium  for  yeast,  moulds 
and  bacteria.  The  Pasteur's  solution  without  sugar  is  the 
same  wdth  the  sugar  omitted. 

Worcester's  Fluid.— This  fluid  is  a  saturated  solution  of 
corrosive  sublimate  (mercuric  chloride)  in  10  per  cent 
formalin.  For  small  animals  and  small  pieces  of  tissue  kill 
for  fifteen  minutes  to  an  hour.  Wash  in  water,  preserve  in 
formalin  or  alcohol.  Especially  good  for  killing  Paramecium 
and  Protozoa.  If  used  hot  Protozoa  and  hydra  are  killed 
instantly. 

Zenker's  Fluid. 


Corrosive  sublimate  (mercuric  chloride)      .      ,  5  g 

Potassium  bichromate       ...  2  o'e 

Water .'.".'  l<X/cc 

Just  before  using  add  glacial  acetic  acid      ...  5  cc 


APPENDIX  161 

Fix  for  six  to  twenty-four  hours,  wash  in  running  water  for 
twelve  to  twenty-four  hours.  Preserve  in  alcohol  80  per- 
cent. 

This  is  one  of  the  standard  killing  mixtures,  and  for  general 
histological  use  it  is  excellent.  It  would  be  well  to  treat  the 
fixed  tissue  in  alcohol  with  iodine  for  twenty-four  hours  to 
remove  all  excess  of  the  mercury  salt.  After  this  the  iodine 
must  be  thoroughly  removed  from  the  tissue  by  several 
changes  of  alcohol. 

Tests  for  Organic  Substances. 

Grape  Sugar  or  Glucose.— Into  a  test  tube  place  the  sub- 
stance to  be  tested,  add  Benedict's  or  Fehling's  solution  and 
boil.  The  appearance  of  a  yellowish  or  red  color  indicates 
the  presence  of  the  grape  sugar. 

Starch.— If  a  substance  containing  starch  is  acted  upon 
by  an  iodine  solution  a  blue  color  will  result.  The  reaction 
takes  place  more  quickly  if  the  substance  has  been  boiled 
and  the  starch  grains  swelled. 

Cellulose.— This  substance  is  common  in  plant  tissues,  in 
the  fibers  and  cell  walls;  cotton  is  almost  pure  cellulose. 
The  section,  or  material,  to  be  tested  for  cellulose  is  treated 
with  a  drop  or  two  of  chloriodide  of  zinc.  Cellulose  is 
colored  violet,  lignified  membranes  a  yellowish  brown, 
membranes  containing  cutin  or  cork  from  yellow  to  yellow- 
ish-brown. 

Fat.— Fats  and  oils  are  stained  black  by  osmic  acid.  A 
1  per  cent  solution  acting  on  a  thin  piece  of  tissue  will  show 
the  reaction  within  a  few  minutes.  Sudan  III  in  aqueous 
solution  will  stain  fat  or  oil  a  yellowish  color,  and  Scharlach 
R  will  give  a  red  color.  These  stains  will  also  act  upon  fat 
preserved  in  formalin.  Ether  or  benzene  may  be  mixed 
11 


162  GENERAL  BIOLOGY 

with  the  substance  to  be  tested  and  allowed  to  remain  for 
a  few  minutes,  then  filtered  and  the  filtrate  evaporated  in 
a  draft.  The  oil,  if  present,  will  be  left  behind  in  the  dish. 
Protein.— Place  the  substance  to  be  tested  in  a  test  tube, 
add  a  few  drops  of  strong  nitric  acid  and  boil.  Cool  and 
carefully  add  a  few  drops  of  ammonia.  A  yellow  color 
appearing  when  the  nitric  acid  is  boiled  and  becoming  a 
deep  orange  on  the  addition  of  the  ammonia  is  an  indication 
of  the  presence  of  the  protein.  This  is  one  of  the  best  and 
most  easily  made  tests  for  protein. 


GLOSSARY 


abdomen.— In  vertebrates  that  part  of  the  trunk  below  or 
behind  the  thorax;  in  invertebrates  the  posterior  region 
of  the  body. 

aboral.— Opposite  the  oral  or  mouth  region. 

achromatin.  — The  material  in  the  nucleus  not  colored  by 
certain  dyes. 

adaptation. —The  condition  of  a  portion  of  the  body  such 
that  it  is  adjusted  or  fitted  to  its  functions. 

adductor.— A  muscle  which  draws  some  part  toward  the 
middle  line  of  the  body. 

alga.— Simple  plants,  one  or  many  celled;  without  definite 
leaves,  stem  or  roots. 

alternation  of  generations.— The  alternation  of  sexual  and 
asexual  forms  in  the  life  history  of  a  plant  or  animal. 

alveolar.— Resembling  little  cells  or  sacs,  a  common  appear- 
ance of  protoplasm. 

amitosis.— Simple  or  direct  division  of  the  nucleus,  a  mere 
pinching  into  two  parts.  Opposed  to  mitosis  or  indirect 
division. 

analogous.— Similarity  of  function. 

anaphase.—  A  stage  in  indirect  division  in  which  the  chromo- 
somes are  pulled  apart  into  two  groups. 

anastomosis.— The  interjoining  or  fusing  of  nerves  or  blood- 
vessels. 

animalcule.— A  microscopic  animal. 


164  GENERAL  BIOLOGY 

anterior.  —At  or  toward  the  front  or  head  end. 

anus.— The  posterior  opening  of  the  digestive  tube. 

aorta.— In  invertebrates  the  chief  artery  of  the  body;    in 

vertebrates  the  large  artery  supplying  the  main  organs 

of  the  body, 
aortic  arch.— The  arch  or  loop  of  the  main  arteries  as  they 

leave  the  heart, 
apopyle.— In  the  sponge  the  opening  of  a  radial  canal  into 

the  central  cavity. 

appendage.— A  subordinate  part  of  an  organ  or  body;  es- 
pecially an  external  organ  or  limb. 

artery.— A  bloodvessel  carrying  blood  away  from  the  heart, 
asexual.— Non-sexual;    reproduction  by  means  other  than 

sexual,  as  by  budding  or  fission, 
aster.— Star.    The  star-like  structure  found  at  the  end  of 

the  spindle  during  mitotic  division  of  the  nucleus, 
asymmetry.— Lack  of  symmetry, especially  absence  of  bilateral 

symmetry. 

B 

bacillus. —A  little  staff.    A  rod-shaped  bacterium. 

barb.— A  hook  or  point  extending  backward,  which  pre- 
vents the  pulling  out  of  the  object. 

bilateral  symmetry.— Symmetrical  with  respect  to  the  right 
and  left  sides. 

biramous.— Having  two  branches,  as  a  typical  crustacean 
appendage. 

bivalve.— Shell  composed  of  two  lateral  valves  or  pieces -as 
the  shell  of  the  clam. 

blastopore.— The  pore  opening  into  the  primitive  gut  of.  a 
developing  animal. 

blastostyle.— That  portion  of  the  fleshy  axis  which  pro- 
duces medusae  in  certain  hydroids. 


GLOSSARY  165 

blastula.  —A  hollow  sphere  of  cells  produced  by  the  develop- 
ment of  the  egg. 

body  cavity.— Coelom;  the  cavity  between  the  digestive 
tube  and  the  body  wall. 

brachial.— Pertaining  to  the  arms. 

branchial.— Pertaining  to  the  gills. 

buccal  groove.— In  infusoria  the  groove  leading  to  the  mouth. 


caecum.— A  tube  or  sac  open  at  one  end  only;  usually  applied 
to  appendages  of  the  digestive  tract. 

calcareous.— Composed  of  lime  or  calcium  carbonate. 

calciferous.— Esophageal  glands  in  the  earthworm  contain- 
ing calcium  carbonate. 

capsule.— A  little  case.  In  hydroids  the  cavity  of  a  sting- 
ing cell  which  contains  the  poison. 

carapace. — A  shell  or  shield  covering  the  head  and  thorax 
of  Crustacea. 

cell.— One  of  the  structural  units  of  a  living  body;  a  mass 
of  protoplasm  containing  a  nucleus. 

centrosome.— The  central  body  or  region  of  an  aster  in 
mitosis. 

cephalothorax.  —  The  region  of  the  body  composed  of  the 
fused  head  and  thorax. 

cerebral.— Pertaining  to  the  cerebrum  or  brain;  in  inverte- 
brates cerebral  ganglia  or  brain. 

chela.— The  pincer-like  claw  of  Crustacea  and  other  arthro- 
pods. 

cbitin.— The  horny  material  forming  the  covering  of  insects 
and  certain  other  animals. 

chlorogog.— Gland  cells  surrounding  the  stomach-intestine 
of  the  earthworm. 


166  GENERAL  BIOLOGY 

chlorophyll.— The  green  coloring  matter  of  plants. 

chloroplast.— A  chlorophyll  body  or  granule. 

chromatin.— The  ingredients  of  the  nucleus  which  stain 
deeply  with  certain  dyes. 

chromosome.— A  distinct  body  formed  from  the  chromatin, 
and  present  only  at  the  time  of  nuclear  division. 

cilia.— Minute,  vibratory,  protoplasmic  processes  on  a  cell. 

circum-esophageal.— About  the  esophagus.  Refers  to  the 
nerve  connectives  joining  the  ventral  cord  and  cerebral 
ganglia  of  invertebrates. 

cleavage.— Splitting  or  division  of  the  egg  cell  at  the  be- 
ginning of  development. 

clitellum.— A  thickened,  glandular  region  of  the  earthworm 
which  secretes  the  egg  case. 

cloaca.— A  chamber  into  which  empty  the  intestine,  kidneys, 
and  reproductive  organs. 

coccus.— A  spherical  bacterium. 

ccelom.— The  body  cavity;  the  space  between  digestive 
tube  and  body  wall. 

coenosarc.— The  fleshy  stalk  or  stem  of  hydroids,  uniting  the 
various  polyps. 

colony.— A  group  of  animals  living  or  growing  together,  the 
various  individuals  being  connected. 

commissure.— A  band  of  nerves  connecting  ganglia  in  in- 
vertebrates; tracts  of  nerve  fibers  within  the  central 
nervous  system  of  vertebrates. 

conjugation.— A  temporary  or  permanent  fusion  of  cells  in 
reproduction. 

contractile  vacuole.— A  pulsating  vacuole  in  protozoa  hav- 
ing an  excretory  function. 

corpuscle.— A  cell  of  an  animal  body  floating  in  a  fluid  or 
separated  by  an  intercellular  matrix. 


GLOSSARY  167 

crop.— The  pouch-like  enlargement  of  the  digestive  tube 
used  to  store  food. 

cuticle.— The  outer  skin.     In  protozoa  the  cell  wall. 

cytology.  —The  science  of  cell  structure  and  function. 

cytoplasm. —The  protoplasm  of  the  cell  proper,  as  con- 
trasted with  the  nucleoplasm,  or  protoplasm  of  the 
nucleus. 

D 

desmid. )  _ 

Y  Minute  unicellular  algse. 

digit.— A  terminal  division  of  an  appendage  of  vertebrates, 

finger  or  toe. 
distal.— Away  from  the  point  of  attachment,  opposed  to 

proximal, 
dorsal.— The  back  or  upper  surface. 

E 

ectoderm.  —The  outermost  layer  of  cells. 

ectoplasm. —The  outer,  denser  protoplasm  in  protozoa. 

embryo. — The  young  of  an  animal  before  its  parts  are  fully 
developed,  and  before  the  commencement  of  inde- 
pendent existence. 

embryology. —The  science  of  the  development  of  animals 
and  plants. 

encyst.— To  enclose  in  a  cyst  or  case,  common  in  protozoa 
and  bacteria  for  protection. 

endopodite.— In  Crustacea  the  branch  of  a  biramous  append- 
age toward  the  median  line  of  me  body. 

enteron.— The  digestive  tube,  especially  the  simple  tract 
of  lower  animals. 

entoderm.— The  inner  tissue  lining  the  enteron  or  digestive 
tube. 


168  GENERAL  BIOLOGY 

entoplasm. —The  •  inner,  more  fluid  protoplasm  of  protozoa. 

enzyme.— An  active  substance  secreted  by  a  living  cell  which 
has  the  property,  under  certain  conditions,  of  bring- 
ing about  changes  in  other  substances  without  itself 
entering  into  the  composition  of  the  substance  which 
results. 

excretion.— Substances  produced  in  the  body  as  the  result 
of  metabolism,  which  are  of  no  further  use  to  the  body. 

excurrent.— A  pore  or  tube  through  which  a  current  passes 
outward. 

exopodite.  —  The  outer  terminal  segment  of  a  biramous 
crustacean  appendage. 

exoskeleton.—  The  external  skeleton  or  shell. 


ferment.— See  Enzyme. 

fertilization.— The  union  of  a  spermatozoon  and  an  ovum. 

fibrillar.— Composed  of  fibers. 

nbro-vascular.— Bundles  in  a  plant  composed  of  fibers  and 

large  vessels  through  which  fluids  or  gases  pass, 
fission.— A  division,  usually  into  two  parts;    the  common 

method  of  reproduction  in  protozoa. 

flagellum.—  A  long,  whip-like,  vibratory  projection  of  a  cell, 
function.— The  appropriate  action  of  any  special   organ  or 

part. 

«  G 

gamete.— A  reproductive  cell  capable  of  union  with  another 
gamete. 

gametophyte.—  A  plant  which  produces  gametes. 

ganglion.— A  group  of  nerve  cells  usually  forming  a  swell- 
ing in  the  course  of  a  nerve. 


GLOSSARY  169 

gastro-vascular.  —  The  inner  cavity  of  hydra,  hydroids  and 
medusae  which  performs  both  digestive  and  circulatory 
functions. 

genital.— Pertaining  to  reproduction  or  the  reproductive 
organs.  . 

germ  layer.— Any  one  of  the  three  embryonic  tissues,  ecto- 
derm, entoderm  or  mesoderm. 

giant  fibers.— A  group  of  large  tubes  in  the  dorsal  portion 
of  the  nerve  cord  of  annelids.  They  may  represent 
degenerated  nerve  fibers  or  supporting  structures. 

gizzard.— A  muscular  stomach  in  which  food  is  crushed  and 
ground. 

gland.— A  part  or  organ  for  secreting  some  substance  to  be 
used  in,  or  eliminated  from,  the  body. 

glottis.— The  opening  from  the  mouth  into  the  trachea. 

gonangium.  —  A  reproductive  individual  in  some  hydroids, 
covered  by  an  enlargement  of  the  perisarc. 

granular. — Composed  of  granules  or  small  grains. 


II 


hermaphrodite.— An  animal  containing  both  male  and  female 

sex  organs. 
histology.— The  science  treating  of  the  microscopic  structure 

of  animal  and  plant  tissues, 
homology.— Similarity  in  structure  and  origin, 
hydranth.— One  of  the  individual  polyps  of  a  hydroid  colony, 
hydroid.  —Resembling  hydra ;  marine,  usually  colonial  animals 

of  the  phylum  Ccelenterata. 
hydrotheca.— The    vase-shaped    expansion    of   the   perisarc 

which   covers   and   protects  the  hydranth   of  certain 

hydroids. 


170  GENERAL  BIOLOGY 

I 

incurrent.— A  pore  or  tube  through  which  water  enters  an 
animal. 

infusoria.— Protozoa  found  in  infusions  of  organic  matter; 
ciliate  protozoa. 

interstitial  cells.— Cells  of  hydra  which  fill  the  spaces  be- 
tween the  bases  of  the  ectodermal  cells. 

irritability.— Susceptibility  of  protoplasm  to  the  influence 
of  stimuli. 


labium.—  One  of  the  mouth  parts  of  insects,  the  lower  lip  or 
second  maxilla. 

labrum.— One  of  the  mouth  parts  of  insects,  the  upper  lip. 

lamella.  —A  thin  plate  or  layer. 

larva.— The  free  living  young  of  an  animal  in  which  develop- 
ment is  accompanied  by  a  metamorphosis. 

lateral.— On  or  toward  the  side. 

ligament.— A  tough  band  which  connects  one  part  to  an- 
other; in  the  clam  the  elastic  band  which  unites  the 
valves  of  the  shell. 

M 

macronucleus.—  The   larger   of  the  two  nuclei   present   in 

ciliated  protozoa. 

mandible. —The  hard  jaw  of  arthropods,  one  of  a  pair, 
mantle.— The  fold  of  skin  covering  the  body  and  secreting 

the  shell  in  molluscs, 
manubrium.  — The    proboscis    or    sac-like    stomach    of    the 

medusa, 
matrix.— The  intercellular  ground  substance  which  separates 

the  cells  in  such  tissues  as  cartilage. 


GLOSSARY  171 

maturation.— Process  of  ripening;  especially  a  stage  in  the 
formation  of  spermatozoa  and  ova. 

maxilla.— One  of  the  mouth  parts  of  arthropods;  in  verte- 
brates the  jaw  bone. 

maxilliped.  —  Foot  jaws.  Thoracic  appendages  of  the  cray- 
fish modified  as  mouth  parts. 

medusa.— The  free  swimming,  sexual  individual  in  the  life 
history  of  hydroids. 

mesentery.— A  thin  fold  of  tissue  which  holds  the  intestine 
in  place  against  the  body  wall. 

mesodenn.—  The  middle  one  of  the  three  germ  layers  formed 
in  the  development  of  most  embryos. 

mesothorax.—  The  middle  segment  of  the  thorax  of  insects. 

metamere.— One  of  the  serially  arranged  body  segments  or 
somites  in  animals  such  as  Annelida  and  Arthropoda. 

metamorphosis.— The  striking  changes  in  form  undergone 
by  certain  animals  in  the  course  of  development  after 
the  commencement  of  a  free  existence.  For  example, 
the  change  from  a  caterpillar  through  a  pupa  into  a 
butterfly,  the  change  of  a  tadpole  into  a  frog. 

metaphase.— The  stage  in  mitosis  during  which  the  chromo- 
somes are  split. 

metathorax.  — The  posterior  somite  of  the  thorax  of  insects. 

micronucleus.  — The  small  nucleus  or  nuclei  found  in  certain 
protozoa,  always  accompanied  by  a  macronucleus. 

mitosis.— Indirect  division  during  which  the  nucleus  under- 
goes complicated  changes,  and  the  chromatin  becomes 
divided  into  equal  halves. 

morphology.— The  science  of  the  form  and  structure  of 
animals  and  plants. 

mucosa.— Mucous  membrane.  An  epithelial  covering  which 
is  kept  moist  by  secretions  of  mucus,  as  in  the  stomach. 


172  GENERAL  BIOLOGY 

N 

nematocyst.—  A  stinging  cell  of  Ccelenterates. 

nephridium. — A   much  coiled  tube  serving  as  a  kidney  in 

annelids  and  other  invertebrates.    Typically  they  are 

paired  segmental  organs. 

nucleolus.—  A  small  dense  spot  within  the  nucleus, 
nucleus.— The  central,  usually  spherical,  portion  of  the  cell 

which  contains  the  chromatin. 


ocellus.— A  simple  eye  of  an  arthropod. 

operculum.—  A  lid  which  closes  the  aperture  of  the  shell  of 

some  snails;    the  covering  of  the  gills  of  a  fish;    the 

skin  which  overgrows  the  gills  of  the  tadpole, 
oral.— Pertaining  to  the  mouth,  opposed  to  aboral. 
organ.— A  part  of  an  organism  capable  of  performing  some 

special  action  which  is  essential  to  the  life  of  the  whole, 
organism.— An  organized  being  or  living  body  capable  of 

independent  existence;     often   the   organism   is   com- 
posed of  organs. 
osculum.—  The  excurrent  opening  in  the  sponge  through 

which  water  passes  to  the  exterior, 
ostiura.— A  mouth-like  opening,  as  the  pores  on  the  outer 

surface  of  the  sponge,  and  the  pores  in  the  heart  of 

arthropods, 
ovary.— The  organ  which  produces  the  ova  or  female  sex 

cells, 
oviduct.— The  duct  or  passageway  from  the  ovary  to  the 

outside  of  the  body, 
ovipositor.— The  organ  by  which  many  insects  deposit  their 

eggs. 
ovum.— The  egg  or  female  sex  cell. 


GLOSSARY  173 


palp  (palpus).— In  arthropods  a  feeler,  especially  the  jointed 

palps  on  the  mouth  parts;    in  the  clam  soft,  fleshy, 

ciliated  flaps  near  the  mouth, 
parapodium.  —  A  fleshy  unsegmented  appendage  of  a  somite 

of  annelids, 
parenchyma. —The  soft  cellular  tissue  of  plants  and  animals. 

In  the  fern  the  pith;   in  flatworms  the  soft  tissue  which 

fills  the  body  cavity, 
pectoral.— Of  or  pertaining  to  the  breast  or  chest,  as  pectoral 

muscles,  pectoral  girdle, 
pelvic.— The  girdle,  in  vertebrates,  which  attaches  the  hind 

legs  to  the  vertebral  column. 

pericardium.— The     membrane  which  surrounds  the  heart, 
perisarc.— The    protective,    horny,    secreted    sheath    about 

hydroids. 
peristome.— A  lip  around  the  mouth  in  Vorticella  and  other 

protozoa, 
peritoneum. —A  smooth  serous  membrane  which  lines  the 

body  cavity  and  covers  the  viscera, 
photosynthesis.  —The  process  by  which  starch  is  manufactured 

in  green  plants,  in  the  presence  of  sunlight, 
planula.  — The  larva  of  many  Coelenterates;    it  is  usually 

oval  in  form  and  covered  with  cilia, 
plasmolysis.  —The  separation  of  the  protoplasm  of  a  cell  from 

its  enclosing  cell  wall, 
plexus.— An  aggregation  of  vessels  or  nerves  forming  an 

intricate  network, 
polyp.  —An  organism  or  a  part  having  a  structure  similar  to 

that  of  the  fresh  water  hydra, 
posterior.— At  or  toward  the  hind  or  tail  end. 
proboscis. —The  long  flexible  sucking  mouth  parts  of  the  bee. 


174  GENERAL  BIOLOGY 

prophase.  — The  preparatory  stage  of  mitosis;    the  period  of 

formation  of  chromosomes  and  spindle, 
prosopyle.— In  the  sponge  a  pore  connecting  the  incurrent 

and  radial  canals, 
prostomium.  —  The  region  which  overhangs  the    mouth  in 

annelids. 

prothorax.— The  first  somite  of  the  thorax  in  insects, 
protoplasm.— The  living  substance, 
protopodite— The  basal  portion  of  a  crustacean   appendage 

from  which  extend  the  two  distal  branches,  exopodite 

and  endopodite. 

protractor.— A  muscle  that  draws  forward, 
pseudopodium.— A   temporary   and    changing   protoplasmic 

projection  in  amoeba  and  similar  protozoa, 
pyrenoid.— Bright   globules   embedded   in   the   chloroplasts 

of  green  algae,  which  function  to  produce  starch. 


radial.— Diverging  from  a  common  center,  as  the   radial 

canals  of  a  medusa. 

retractor.— A  muscle  which  draws  parts  back, 
rhizome.— The  underground  stem  of  the  fern. 

S 

sclerenchyma.— Woody  or  hard  cells  in  plants  which  serve 
to  stiffen  and  support. 

secretion.— A  substance,  made  by  parts  or  organs  of  an 
animal,  which  is  of  use  within  the  body. 

septum.— A  wall  or  partition,  especially  the  partitions  divid- 
ing the  ccelom  of  annelids. 

serosa.— Serous  membrane;  a  delicate  tissue  which  lines 
closed  cavities  and  is  bathed  by  lymph. 


GLOSSARY  175 

seta.— A  chitinous  spine  or  bristle  in  annelids  used  in  lo- 
comotion, 
sexual.— Of    or    pertaining    to    sex.    Sexual    reproduction 

involves  the  two  sexes  and  the  two  kinds  of  sex  cells, 

spermatozoa  and  ova. 

skeleton.— The  bony  framework  which  supports  the  verte- 
brate body, 
somite.— A  metamere;    one  of  the  serial  segments  of  which 

an  animal  like  the  insect  or  annelid  is  composed, 
spermatozoon. —The  male  sex  cell, 
spicule.— A   small,    spine-like   skeletal   body   embedded   in 

the  wall  of  sponges. 
spindle.— The  barrel-shaped  structure  of  threads  in  a  cell 

at  the  time  of  the  mitotic  division  of  the  nucleus, 
spiracle.— One  of  the  openings  to  the  tracheae  or  air  tubes 

of  insects. 

spirillum.— A  spiral-like  bacterium, 
spore.— An  asexually  produced  body  which  gives  rise  to  a 

new  organism, 
sternum.— In  vertebrates  the  breast  bone;    in  arthropods 

the  ventral  portion  of  the  exoskeleton  of  a  somite, 
stomach-intestine.— The  posterior  portion  of  the  digestive 

tube  in  annelids,  with  the  functions  both  of  stomach 

and  intestine, 
symmetry.— Orderly  and  similar  distribution  of  parts  in  an 

organism, 
system.— An  assemblage  of  parts  or  organs  essential  to  the 

performance  of  some  particular  function. 


tarsus.— The  jointed  foot  of  an  insect. 

telophase.— The  stage  in  mitosis  in  which  the  cell  is  divided, 
and  the  nucleus  reformed  into  a  typical  spherical  form. 


176  GENERAL  BIOLOGY 

tentacle.— A    slender,    unsegmented,    tactile   or    prehensile 

organ  near  the  mouth, 
tergum.— The  dorsal  portion  of  the  exoskeleton  of  a  somite 

in  arthropods. 

testis.— The  male  reproductive  organ, 
thorax.— The  middle  of  the  three  divisions  of  the  body  of 

an  insect. 

tissue.— A  group  of  similar  cells  having  a  similar  function, 
trachea.— The  windpipe  of    vertebrates;    a   branching  air 

tube  of  insects. 
trichocyst.—  A  sac  or  rod-like    body  in  the  ectoplasm  of 

Paramecium. 
tubule.— A  small  tube, 
tympanic  membrane.— The  ear   drum   or   membrane   of  an 

auditory  organ, 
typhlosole.—  A  longitudinal   fold   in  the   intestinal    wall  of 

annelids,  molluscs  and  certain  other  animals. 

U 

umbo.— One  of  the  lateral  prominences  just  above  the  hinge 

of  a  bivalve  mollusc  shell, 
ureter.— The  duct  of  the  kidney, 
urino-genital.— Relating  to  the  urinary  and   genital  organs, 

as  urino-genital  artery. 


vacuole.—  A  globular  space  within  a  cell  containing  a  gas 

or  liquid, 
valve.— One  of  the  pieces  of  the  shell  of  a  clam;    a  flap  or 

fold  within  a  cavity  which  permits  the  passage  of  a 

liquid  in  one  direction  only. 


GLOSSARY  177 

variation.— A  modification,  alteration,  or  deviation  from  the 

typical  or  usual  condition, 
vein.— A  vessel  which  carries  blood  to  the  heart;   one  of  the 

ribs  in  the  wings  of  insects. 
velum.— A  circular  membrane  that  partly  incloses  the  space 

beneath  the  umbrella  in  medusae. 
ventral.  —At  or  toward  the  under  or  belly  surface, 
viscera.— The  internal  organs  taken  as  a  whole. 


yeast.— A  unicellular,  colorless  plant  which  causes  an  alco- 
holic fermentation  of  carbohydrates. 


zob'id.—  One  of  the  single  individuals  in  a  colony  of  animals, 
zobspore.—  A  spore  provided  with  one  or  more  flagella  by 

which  it  swims  in  the  water, 
zygospore.—  A  spore  formed  by  the  union  of  two  zoospores, 

or  by  union  of  protoplasm  from  two  plants. 


INDEX. 


ABDOMEN,  110,  116 

Acetic  acid,  155 

Achromatin,  50 

Aciculum,  96 

Actinozoa,  141 

Adductor  muscle,  126,  128 

Adrenal  gland,  30 

Alcohol,  155,  156 

Alimentary  canal.      See  Digestive 

System. 
Alternation  of  generations,  82,  84, 

101 

Amitosis,  51 
Amoeba,  54,  147 
Amphibia,  145 
Anaphase,  51 
Anilin  dye,  156 
Animal  pole,  42 
Annelida,  143 
Antenna,  112,  116,  122 

cleaner,  123 
Antheridium,  102 
Antherozoids,  102 
Anus,  88,  111,  128,  133,  137 
Aorta,  32,  128 
Aortic  arch,  31 
Apis,  121 
Apopyle,  73    • 
Appendage,  111,  116,  123 
Appendix,  147 
Arachnida,  144 
Archegonium,  103 
Artery,  31,  32,  128 
Arthropoda,  144 
Asexual,  69,  78,  81,  101 
Aster,  51 
Asteroidea,  142 
Auricle,  28,  128 
Aves,  145 
Axone,  40 


BACILLUS,  107 

Bacteria,  107 

Bast,  100 

Bee,  121 

Benedict's  solution,  156 

Bile  duct,  29 

sac,  29 

Bladder,  29,  138 
Blastopore,  43 
Blastostyle,  84 
Blastula,  52 
Blood,  33 

Borax  carmine,  157 
Bouin's  fluid,  157 
Brachial,  32,  36,  37 
Brain,  35,  114,  119,  138 
Branchiostegal,  137 
Buccal  groove,  58 
Budding,  76,  81,  105 


CAECUM,  118,  138 

Calciferous  gland,  91 

Cambarus,  110 

Campanularia,  83,  84 

Carapace,  110 

Carotid,  31,  32 

Cartilage,  39 

Cell,  45,  50 

Cellulose,  161 

Centrosome,  51 

Cephalopoda,  144 

Cephalo  thorax,  110 

Cerebellum,  35,  139 

Cerebral  ganglia,  91,  97,  114,  129 

hemisphere,  35,  138 
Cestoda,  142 
Chsetopoda,  143 


180 


INDEX 


Chloretone,  157 

Chloriodide  of  zinc,  157 

Chlorogogue,  92 

Chlorophyll,  48,  66,  71,  98 

Chloroplast,  66,  71,  98 

Choanocyte,  74 

Chromatin,  50 

Chromosome,  51 

Cilia,  49,  58 

Ciliated  epithelium,  39 

Circulation  of  protoplasm,  48,  60 

Circulatory  system,  31,  89,  93,  113, 

128 

Cirrus,  95 
Clam,  125,  151 
Classification,  140 
Clearing,  155 
Cleavage,  42,  52 
Clitellum,  87 
Cloaca,  31 
Cnidocil,  76 
Coccus,  107 
Cocoon,  87 
Crelenterata,  141 
Coeliaco-mesenteric,  33 
Co3lom,  28,  89,  92,  96 
Crenosarc,  80 
Collection  of  material,  147 
Colony,  68,  76,  80 
Columella,  134 
Columnar  epithelium,  38,  41 
Commissure,  97,  114,  129 
Conjugation,  61,  64,  71,  147 
Contractile  vacuole,  55,  59,  63 
Contractility,  77 
Corpuscle,  38 
Coxa,  117 
Cranial  nerve,  37 
Crayfish  110,  151 
Crop,  90,  96,  118 
Crustacea,  144 
Cutaneous,  32 
Cuticle,  58,  62,  92 
Cystic  duct,  28 
Cytology,  50 
Cytoplasm,  50 


DEHYDRATION,  154,  155 
Dentary,  136 
Development,  53,  103 
Diaphragm,  23 


Digestive  system,  90,  113,  118,  129 
Digit,  27 
!  Dissection,  21 
Dorsal  aorta,  32,  33 

root,  37 
Drawings,  18 
Drone,  124 
Dura  mater,  35 


EAR,  26 

Earthworm,  87,  149 

Echinodermata,  141 

Echinoidea,  142 

Ectoderm,  52,  76,  81,  84 

Ectoplasm,  54,  58 

Egg,  30,  42,  52,  74,  78,  81,  90,  96, 

103 

Embryo  52 
Embryology,  42 
Endopodite,  111 
Enteron,  76 

Entoderm,  52,  76,  81,  84 
Entoplasm,  54,  58 
Epidermis,  92,  99 
Epigastric,  33 
Epithelium,  38,  74,  92 
Esophageal  artery,  33 
Esophagus,  27,  90,  113,  118,  129, 

137 

sEustachian  tube,  27 
:  Excretory  system,  88,  91,  114,  119, 

129      ' 

jExcurrent,  73,  127 
Exopodite,  111 
Exoskeleton,  110,  116,  127 
Eye,  26,  95,  116,  121,  133,  136 


FAT,  161 

body,  30 
Feeding,  115,  131 
Fehling's  solution,  158 
Femoral,  34 
Femur,  117 
Fermentation,  106 
Fern,  98 
Fertilization,  52 
Fibrovascular,  100 
Fins,  136 


INDEX 


181 


Fish,  135 

Hydroid,  80,  83,  149 

Fission,  60,  64 

LLydrorhiza,  80 

Fixation,  154 

Hydrotheca,  83 

Flagellated  chamber,  74 
Flagellum,  69,  74 

Hydrozoa,  141 
Hypostome,  83 

Focusing,  23,  24 

Food  vacuole,  55,  59,  63 

Foot,  27,  117,  123,  128,  133 

I 

Formalin,  158 

ILIAC,  33 

Frog,  26,  152 

Incurrent,  73,  127 

Frond,  98,  99 

Infundibulum,  36 

Infusoria,  57,  141 

G 

Injection  of  frog,  152 

mass,  159 

GAMETE,  69 

Insecta,  144 

Gametophyte,  101 

Interstitial,  79 

Ganglion,  36,  91,  97,  114,  119,  129 

Intestine,  29,  113,  118,  129,  138 

Gastric,  41,  85,  118 

Iodine,  159 

Gastropoda,  143 

Irritability,  60,  64,  77 

Gastrula,  52 

Germ  layers,  52,  53 

Gephyrsea,  143 

K 

Gill,  43,  95,  112,  127,  137 
Gizzard,  91 

KIDNEY,  30,  91,  114,  129,  138 

Gland  cell,  39,  79 

Killing  reagent,  154,  157,  158,  160 

Glossa,  122 

Glossary,  163 

Glottis,  27 

L 

Glycerin,  158 

Goblet  cell,  39 

LABIUM,  116,  122 

Gonangium,  84 

Labrum,  116,  122 

Gonionemus,  85 

Lamellibranchiata,  143 

Grantia,  73 

Laryngeal,  32 

Grape  sugar,  161 

Lateral  line,  137 

Grasshopper,  116,  150 

Lens  of  microscope,  23 

Growth,  105,  109,  125 

Ligament,  125 

Lime  water,  159 

Liver,  29,  113,  129,  137 

H 

Locomotion,  77,  114 

Lumbar,  33,  36,  37 

HAY  infusion,  147 

Lumbricus,  87 

Head,  26,,  95,  116,  121 

Lung,  27,  29 

Heart,  28,  89,  113,  120,  132,  133, 

Lymph  space,  28 

138 

Lyons  Blue,  159 

Heliotropism,  77 

Helix,  133 

Hematoxylin,  158 

M 

Hirudinea,  143 

Histology,  38,  92,  99 

MALPIGHIAN  tubule,  119 

Holothuroidea,  142 

Mammalia,  145 

Homology,  112                                   Mandible,  116,  122 
Honev  bee,  121                                   Mantle,  127 

Hydra,  75,  148 

Manubrium,  85 

Hydranth,  80,  83 

Mastigophora,  141 

182 

Maturation,  52 
Maxilla,  112,  116,  122 
Maxillary,  27,  136 
Maxilliped,  112 
Medulla,  35,  139 
Medusa,  81,  84,  85 
Mesentery,  31,  138 
Mesoderm,  52 
Mesothorax,  117 
Metamorphosis,  44 
Metaphase,  51 
Metatarsus,  123 
Metathorax,  117 
Methyl  green,  160 
Methylen  blue,  160 
Microscope,  22,  25 
Midrib,  99 
Mitosis,  51 
Mollusca,  143 
Mounting,  153 


INDEX 


Mouth,  26,  27,  75,  85,  88,  111,  116,  Parapodium,  95 


Olfactory,  35,  138 
Operculum  (opercle),  43,  134,  137 
Ophiuroidea,  142 
Optic  chiasma,  36 
lobe,  35,  138 
Organ,  45 
Osculum,  73 
Ostia,  73 
Ovary,  29,  78,  90,  113,  119,   130, 

Oviduct,  29,  88,  90,  119 
Ovipositor,  118 
Ovum.     See  Egg. 


PALP,  95,  122,  124,  128 
Pancreas,  29 
Paramecium,  57,  147 


118,  122,  128,  129,  136 
Movement,  55,  59,  63,  93,  120 
Mucosa,  41 

Muscle,  39,  41,  92,  96,  126,  128 
Myriapoda,  144 


N 

XACREOTJS,  126 
Xemathelminthes,  142 
Xematocyst,  76,  81,  84,  85 
Xephridia,  91 
Xereis,  95 


Parenchyma,  100 
Parthenogonidia,  69 
Pasteur's  solution,  105,1160 
Pectoral,  28,  136 
Pedal  ganglion,  129 
Pelvic,  30 
Pennaria,  80 
Pericardium,  28,  128 
Periostracum,  126 
Perisarc,  80,  83 
Peristome,  62 
Peritoneum,  31,  41,  92 
Peroneal  artery,  34 
Pharynx,  90,  96 


Xerve  cord,  91,  92,  93,  97,  114,  119  Phloem,  100 

tissue,  40  Photosynthesis,  71 

Xervous  system,  34,  91,  114,  119,  Physiology,  55,  59,  63,  69,  71,  77, 
129,  138  93,  104,  108,  114,  120,  130 

Pia  mater,  35 
Pineal  gland,  35,  139 
Pinna,  98,  99 
Pinnule,  98,  99 


Xeural  groove,  43 
Xormal  salt,  160 
Xostrils,  26,  27,  136 
Xotes  and  drawings,  18 
Xucleolus,  50 


,      , 
^Pisces,  144 


Xucleus,  50,  55,  59,  63,  66,  71,  104  Pituitary,  36 
Xutrition,  55,  60,  78,  120,  131         |Planula,  84 
;  Plasma,  38 
Plasmolysis,  71 


OBELIA,  83    . 
Objective,  23 
Occipito-vertebral,  32 
Ocellus,  116,  122 
Ocular,  '23 


Platyhelminthes,  142 
Pleurococcus,  66 
Plexus,  37 
Pollen  basket,  123 

brush,  123 

comb,  123 


INDEX 


183 


Pollen  spur,  123 
Pond  scum,  70 
Porifera,  141 
Premaxillary,  136 
Preparation  of  material,  147 
Prismatic,  126 
Proboscis,  83 
Prophase,  51 
Prosopyle,  74 
Prostomium,  87,  95 
Protein,  162 
Prothallium,  102 
Prothorax,  117 
Protoplasm,  47,  66,  104 
Protopodite,  111 
Protozoa,  68,  140 
Protractor  muscle,  126,  128 
Pseudopodium,  54 
Pteris,  98 
Pulmonary,  31,  32 
Pyrenoid,  71 


QUEEN,  124 


RADIAL  canal,  74,  85 

Rana,  26 

Reagent,  155 

Recto-vesical,  33 

Reproduction,  56,  60,  64,  66,  71, 

78,  81,  89,  101,  113,  119,  130,  138 
Reptilia,  145 
Respiration,  29,  43,  112,  115,  118, 

120,  127,  133,  137 
Retractor  muscle,  126,  128 
Rhizome,  98,  99 
Rhizopoda,  140 


S 


SALT  solution,  160 

Sand  worm,  95 

Sciatic,  34,  37 

Sclerenchyma,  100 

Scyphozoa,  141 

Segmentation.     See  Cleavage. 

Sensitiveness,  56,  93,  115,  120, 

Septa,  89,  96 

Seta,  88,  96 

Sexual,  69,  78,  81,  101 


Shell,  125,  126,  133 

Sieve  tube,  100 

Simis  venosus,  28 

Siphon,  127,  131 

Slides,  mounting,  153 

Snail,  133,  152 

Somite,  87,  116 

Sperm  duct,  88 

Spermatozoa,  52,  74,  78,  81,  90,  96 

Spicule,  73 

Spinal  cord,  35,  40,  139 

nerve,  37,  139 
Spiracle,  43,  117 
Spiral  vessel,  101 
Spirillum,  107 
Spirogyra,  70 
Spleen,  29,  138 
Sponge,  73 

Sporangium,  101,  102 
Sporophyte,  101 
Sporozoa,  141 
Squamous  epithelium,  38 
Staining,  154,  156,  157,  158,  159, 

160 
Starch,  46,  70,  161 

injection  mass,  159 
Starfish  egg,  50,  52 
Sternum,  117 
Sting,  124 
Stipe,  99 
Stomata,  99 

Stomach,  29,  41,  113,  118,  129,  137 
Stomach-intestine,  91,  92,  96 
Subclavian,  32 
Submucosa,  41 
Sugar,  156,  158,  160,  161 
Sympathetic  nerve,  36 
Systemic  arch,  31,  32 


TADPOLE,  43 

Tarsus,  117,  123 

Teeth,  27,  96,  114,  126,  136 

Telophase,  51 

Telson,  110 

Tentacle,  75,  80,  83,  85,  95,  133 

Tergum,  117 

Testis,  30,  78,  90,  113, 119, 130,  138 

Tests  for  organic  substances,  161 

Thalamencephalon,  35,  138 

Thorax,  116,  117 

Tibia,  117 


184 


INDEX 


Tibial  artery,  34 
Tissue,  38,  45 
Tongue,  27,  122,  136 
Trachea,  27,  118 
Tracheid,  101 
Trematoda,  142 
Trichocyst,  58 
Trichome,  99 
Trochanter,  117 
Trancus  arteriosus,  28,  31 
Trunk  27 
Turbellaria,  142 
Tympanum,  26,  117 
Typhlosole,  91,  92 


UMBO,  125 
Unio,  125 
Ureter,  30 
Urino-genital,  30,  33 


VACUOLE,  55,  59,  63,  104 
Vegetative  pole,  42 
Vein,  34,  99,  117,  123,  129 
Velum,  85 


Ventral  root,  37 
Ventricle,  28,  35,  128 
Venus,  125 
Vertebrata,  144 
Vestibule,  63 
Visceral,  129 
Volvox,  68 
Vomerine,  27 
Vorticella,  62,  148 


WAX  shears,  123 
Wing,  117,  123 
Worcester's  fluid,  160 
Worker,  124 


YEAST,  104 

Yolk,  42,  50 

plug,  43 


Z 


ZENKER'S  fluid,  160 
Zinc  chloriodide,  157 
Zooid,  80 
Zoospore,  67 
^ygospore,  72 


DC  SOUTHERN  REGIONAL  LIBRARY  FACILITY 


AA    000480804    4 


SOUTHERN 

UNIVERSITY  OF  CALIFORN 

LIBRARY, 

COS  ANGELES.  CALIF 


